The Crassulaceae (, from Latin ''crassus'', thick), also known as the crassulas, the stonecrops or the orpine family, are a diverse
family
Family (from ) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). It forms the basis for social order. Ideally, families offer predictabili ...
of
dicotyledon
The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two groups into which all the flowering plants (angiosperms) were formerly divided. The name refers to one of the typical characteristics of the group: namely, ...
angiosperm
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed within a fruit ...
s primarily characterized by
succulent
In botany, succulent plants, also known as succulents, are plants with parts that are thickened, fleshy, and engorged, usually to retain water in arid climates or soil conditions. The word ''succulent'' comes from the Latin word ''sucus'', meani ...
leaves and a form of
photosynthesis
Photosynthesis ( ) is a system of biological processes by which photosynthetic organisms, such as most plants, algae, and cyanobacteria, convert light energy, typically from sunlight, into the chemical energy necessary to fuel their metabo ...
known as
crassulacean acid metabolism
Crassulacean acid metabolism, also known as CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions that allows a plant to photosynthesize during the day, but only exchange gases at night. ...
(CAM), in which plants photosynthesize in the daytime and exchange gases during the cooler temperatures of the night. The blossoms of crassulas generally have five floral parts. Crassulaceae are usually
herbaceous
Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials.
Definitions of "herb" and "herbaceous"
The fourth edition of ...
, though there are some
subshrub
A subshrub (Latin ''suffrutex'') or undershrub is either a small shrub (e.g. prostrate shrubs) or a perennial that is largely herbaceous but slightly woody at the base (e.g. garden pink and florist's chrysanthemum). The term is often interch ...
s, and relatively few
tree
In botany, a tree is a perennial plant with an elongated stem, or trunk, usually supporting branches and leaves. In some usages, the definition of a tree may be narrower, e.g., including only woody plants with secondary growth, only ...
s or
aquatic plant
Aquatic plants, also referred to as hydrophytes, are vascular plants and Non-vascular plant, non-vascular plants that have adapted to live in aquatic ecosystem, aquatic environments (marine ecosystem, saltwater or freshwater ecosystem, freshwater ...
s.
The Crassulaceae is a medium-sized,
monophyletic
In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria:
# the grouping contains its own most recent co ...
family in the core
eudicots
The eudicots or eudicotyledons are flowering plants that have two seed leaves (cotyledons) upon germination. The term derives from ''dicotyledon'' (etymologically, ''eu'' = true; ''di'' = two; ''cotyledon'' = seed leaf). Historically, authors h ...
clade, along with the order
Saxifragales
Saxifragales is an order (biology), order of flowering plants in the Superrosids, superrosid clade of the eudicots. It contains 15 Families (biology), families and around 100 genera, with nearly 2,500 species. Well-known and economically import ...
, whose diversity has made infrafamilial classification very difficult. The family includes approximately 1,400
species
A species () is often defined as the largest group of organisms in which any two individuals of the appropriate sexes or mating types can produce fertile offspring, typically by sexual reproduction. It is the basic unit of Taxonomy (biology), ...
and 34–35
genera
Genus (; : genera ) is a taxonomic rank above species and below family as used in the biological classification of living and fossil organisms as well as viruses. In binomial nomenclature, the genus name forms the first part of the binomial s ...
—depending on the circumscription of the genus ''
Sedum
''Sedum'' is a large genus of flowering plants in the family Crassulaceae, members of which are commonly known as stonecrops. The genus has been described as containing up to 600 species, subsequently reduced to 400–500. They are leaf succule ...
''—distributed over three
subfamilies
In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end botanical subfamily names with "-oideae", and zool ...
. Members of the Crassulaceae are found worldwide, though are mostly concentrated in the
Northern Hemisphere
The Northern Hemisphere is the half of Earth that is north of the equator. For other planets in the Solar System, north is defined by humans as being in the same celestial sphere, celestial hemisphere relative to the invariable plane of the Solar ...
and
Southern Africa
Southern Africa is the southernmost region of Africa. No definition is agreed upon, but some groupings include the United Nations geoscheme for Africa, United Nations geoscheme, the intergovernmental Southern African Development Community, and ...
(where the most species are found). They are adapted to thrive in typically dry, arid (hot or cold) areas where water may be scarce, and richer, organic substrates may be at a minimum or nonexistent. The ''
Sempervivum
''Sempervivum'' () is a genus of about 40 species of flowering plants in the family (biology), family Crassulaceae, commonly known as houseleeks. Other common names include liveforever (the source of the taxonomical designation ''Sempervivum'', l ...
'' (houseleeks) of Central and Southern Europe, or the ''
Orostachys
''Orostachys'' is a genus of the succulent family Crassulaceae (stonecrop family) that contains about 15 species. It is a biennial herb growing in China, Japan, Kazakhstan, Korea, Mongolia, Russia. Eight species occur in China.
Description
''Or ...
'' (dunce-caps) of Asia, for example, grow in rocky crevices at higher elevations, where soil is at a minimum but precipitation, sun exposure, and winds may be intense; these plants have thus adapted to absorb water by having succulent leaves, despite living often on slopes or near-vertical cliff faces, from which water typically drains quickly. Their roots are adhesive and grip to any rock, dirt, wood or other surface they come into contact with, while also gleaning minerals from said material. Seedlings that may sprout near more permanent sources of water, such as pooling rainwater or
seeps
A petroleum seep is a place where natural liquid or gaseous hydrocarbons escape to the Earth's atmosphere and surface, normally under low pressure or flow. Seeps generally occur above either natural terrestrial or underwater petroleum accumul ...
, may experience rot or discoloration over time, and not survive.
Crassulaceae are mainly
perennial
In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...
, and have huge global economic importance as collectible specimens, and as indoor and outdoor
garden plant
Ornamental plants or ''garden plants'' are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars th ...
s. Many species in the family, especially of the African genera, have highly unusual (for plants) and otherworldly appearances, often with interesting textures (fuzzy, hairy, spiky, scaly) or curious nodules or growths, all of which are typically the result of environmental adaptations, such as "fuzzy" ''
Kalanchoe tomentosa
''Kalanchoe tomentosa'', also known as pussy ears or panda plant, is a succulent plant in the genus ''Kalanchoe''. A native of Madagascar, ''Kalanchoe tomentosa'' has many different cultivars such as 'Chocolate Soldier', 'Golden Girl', 'Black Ti ...
'' utilizing its hairs as a sunscreen. Apart from some sensitive species, most are quite hardy, typically needing only minimal care. For every alien-looking species, there are just as many others with a more "conventional", rosette growth habit, something reflected in many common names, such as 'Black Rose', another name for the common ''
Aeonium arboreum
''Aeonium arboreum'', the tree aeonium, tree houseleek, or Irish rose, is a succulent, Subtropics, subtropical subshrub in the flowering plant family Crassulaceae.
Description
''Aeonium arboreum'' grows as a less branched subshrub and reaches s ...
'' var. 'Swartzkopf'.
Well-known genera and species include the many forms of ''
Crassula ovata
''Crassula ovata'', commonly known as jade plant, lucky plant, money plant or money tree, is a succulent plant with small pink or white flowers that is native plant, native to the KwaZulu-Natal and Eastern Cape provinces of South Africa, and Moz ...
'' ('Jade', 'Money Plant' or 'Friendship Tree'), ''
Kalanchoe blossfeldiana
''Kalanchoe blossfeldiana'' is a commonly cultivated evergreen house plant of the genus ''Kalanchoe'' native to Madagascar. It is known by the English common names flaming Katy, Christmas kalanchoe, florist kalanchoe and Madagascar widow's-thrill ...
'' (florists' or supermarket-kalanchoe); ''
Cotyledon
A cotyledon ( ; ; "a cavity, small cup, any cup-shaped hollow",
gen. (), ) is a "seed leaf" – a significant part of the embryo within the seed of a plant – and is formally defined as "the embryonic leaf in seed-bearing plants, one or mor ...
'', such as 'Chalk Fingers' and '
Pig's Ear', ''
Sempervivum
''Sempervivum'' () is a genus of about 40 species of flowering plants in the family (biology), family Crassulaceae, commonly known as houseleeks. Other common names include liveforever (the source of the taxonomical designation ''Sempervivum'', l ...
'' such as
cobweb houseleek (or
hen-and-chicks) and ''
S. calcareum'', and ''
Aeonium
''Aeonium'', the tree houseleeks, is a genus of about 35 species of succulent, subtropical plants of the family Crassulaceae. Many species are popular in horticulture. The genus name comes from the ancient Greek αἰώνιος / aiōnios (ageles ...
'' such as ''
A. haworthii'' (and its popular
variegate 'Kiwi'), ''
A. arboreum,
A. canariense,
A. urbicum''; ''
Monanthes
''Monanthes'' is a genus of small, succulent, subtropical plants of the family Crassulaceae. Most species in the genus are endemic to the Canary Islands, with one species also endemic to the Savage Islands and another to the High Atlas mountains ...
'', ''
Umbilicus
Umbilicus may refer to:
*The navel or belly button
*Umbilicus (mollusc), a feature of gastropod, Nautilus and Ammonite shell anatomy
*Umbilicus (plant), ''Umbilicus'' (plant), a genus of over ninety species of perennial flowering plants
*Umbilicus ...
'' (pennywort), ''
Bryophyllum
''Bryophyllum'' (from the Greek ''bryon/bryein'' = sprout, ''phyllon'' = leaf) is a group of plant species of the family (biology), family Crassulaceae native to Madagascar. It is a Section (botany), section or subgenus within the genus ''Kalan ...
'', ''
Echeveria
''Echeveria'' is a large genus of flowering plants in the family (biology), family Crassulaceae, native plant, native to semi-desert areas of Central America, Mexico and northwestern South America.
Description
Echeveria plants are evergreen. Flo ...
'', ''
Sedum
''Sedum'' is a large genus of flowering plants in the family Crassulaceae, members of which are commonly known as stonecrops. The genus has been described as containing up to 600 species, subsequently reduced to 400–500. They are leaf succule ...
'' and ''
Dudleya
''Dudleya'', commonly known as liveforevers, is a genus of rosette-forming succulent plants in the stonecrop family, Crassulaceae, consisting of about 68 taxa in southwestern North America and Guadalupe Island. The species come in many forms, so ...
''.
Description
General: Crassulaceae is a family of
morphologically diverse terrestrial
perennial
In horticulture, the term perennial ('' per-'' + '' -ennial'', "through the year") is used to differentiate a plant from shorter-lived annuals and biennials. It has thus been defined as a plant that lives more than 2 years. The term is also ...
, rarely annual or
hapaxanthic
Monocarpic plants are those that flower and set seeds only once, and then die.
The term is derived from Greek (', "single" + , "fruit" or "grain"), and was first used by Alphonse de Candolle. Other terms with the same meaning are ''hapaxanth'' a ...
(flowering once in a lifetime),
flowering plant
Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (). The term angiosperm is derived from the Ancient Greek, Greek words (; 'container, vessel') and (; 'seed'), meaning that the seeds are enclosed with ...
s that demonstrate
xerophytic
A xerophyte () is a species of plant that has adaptations to survive in an environment with little liquid water. Examples of xerophytes include cactus, cacti, pineapple and some gymnosperm plants. The morphology (biology), morphology and physiology ...
adaptations, with thick
succulent
In botany, succulent plants, also known as succulents, are plants with parts that are thickened, fleshy, and engorged, usually to retain water in arid climates or soil conditions. The word ''succulent'' comes from the Latin word ''sucus'', meani ...
leaves
A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...
, a thick waxy
cuticle
A cuticle (), or cuticula, is any of a variety of tough but flexible, non-mineral outer coverings of an organism, or parts of an organism, that provide protection. Various types of "cuticle" are non- homologous, differing in their origin, structu ...
and
Crassulacean acid metabolism
Crassulacean acid metabolism, also known as CAM photosynthesis, is a carbon fixation pathway that evolved in some plants as an adaptation to arid conditions that allows a plant to photosynthesize during the day, but only exchange gases at night. ...
. Crassulaceae are generally
herbaceous
Herbaceous plants are vascular plants that have no persistent woody stems above ground. This broad category of plants includes many perennials, and nearly all annuals and biennials.
Definitions of "herb" and "herbaceous"
The fourth edition of ...
but there are some
subshrubs
A subshrub (Latin ''suffrutex'') or undershrub is either a small shrub (e.g. prostrate shrubs) or a perennial that is largely herbaceous but slightly woody plant, woody at the base (e.g. garden pink and florist's chrysanthemum). The term is ofte ...
, and relatively few treelike,
epiphytic
An epiphyte is a plant or plant-like organism that grows on the surface of another plant and derives its moisture and nutrients from the air, rain, water (in marine environments) or from debris accumulating around it. The plants on which epiphyt ...
(growing on surface of plants),
scandent
A vine is any plant with a growth habit of trailing or scandent (that is, climbing) stems, lianas, or runners. The word ''vine'' can also refer to such stems or runners themselves, for instance, when used in wicker work.Jackson; Benjamin; Day ...
(vine like) or
aquatic plants
Aquatic plants, also referred to as hydrophytes, are vascular plants and non-vascular plants that have adapted to live in aquatic environments ( saltwater or freshwater). In lakes, rivers and wetlands, aquatic vegetations provide cover for aquat ...
. Most species are herbaceous leaf succulents, with regular 5 part (penta
merous Merosity (from the greek "méros," which means "having parts")) refers to the number of component parts in a distinct whorl of a plant structure. The term is most commonly used in the context of a flower where it refers to the number of sepals in a ...
or fivemerous)
flowers
Flowers, also known as blooms and blossoms, are the reproductive structures of flowering plants ( angiosperms). Typically, they are structured in four circular levels, called whorls, around the end of a stalk. These whorls include: calyx, m ...
,
isomerous free
carpels
Gynoecium (; ; : gynoecia) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) ...
and one or two
whorls
A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs).
In nature
File:Photograph and axial plane floral diagram ...
of
stamens
The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10
Morphology and terminology
A stamen typically consists of a stalk called the filamen ...
.
Vegetative:
Stems are sometimes succulent, as may also be the underground
caudices
A caudex (: caudices) of a plant is a stem, but the term is also used to mean a rootstock and particularly a basal stem structure from which new growth arises.pages 456 and 695
In the strict sense of the term, meaning a stem, "caudex" is most o ...
(rootstock), and may form
rhizomes
In botany and dendrology, a rhizome ( ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...
or
corms
Corm, bulbo-tuber, or bulbotuber is a short, vertical, swollen, underground plant stem that serves as a storage organ that some plants use to survive winter or other adverse conditions such as summer drought and heat ( perennation).
The word '' ...
.
Bulbils
A bulbil (also referred to as a bulbel, bulblet, and/or pup) is a small, young plant that is reproduced vegetatively from axillary buds on the parent plant's stem or in place of a flower on an inflorescence. These young plants are clones of the ...
may form along the stem or leaf margins. The leaf arrangement is
opposite
In lexical semantics, opposites are words lying in an inherently incompatible binary relationship. For example, something that is ''even'' entails that it is not ''odd''. It is referred to as a 'binary' relationship because there are two members i ...
and
decussate
Decussation is used in biological contexts to describe a crossing (due to the shape of the Roman numeral for ten, an uppercase 'X' (), ). In Latin anatomical terms, the form is used, e.g. .
Similarly, the anatomical term chiasma is named aft ...
or alternate and spiral, and they are frequently aggregated into
rosettes. The leaf shape is simple (rarely
pinnate
Pinnation (also called pennation) is the arrangement of feather-like or multi-divided features arising from both sides of a common axis. Pinnation occurs in biological morphology, in crystals, such as some forms of ice or metal crystals, and ...
) and usually entire, or crenate to broadly lobed, sometimes dentate or more deeply incised, glabrous (smooth) or tomentose. In cross section the leaf blades are flat or round. They may be
sessile
Sessility, or sessile, may refer to:
* Sessility (motility), organisms which are not able to move about
* Sessility (botany), flowers or leaves that grow directly from the stem or peduncle of a plant
* Sessility (medicine), tumors and polyps that ...
or
petiolate.
Stipules
In botany, a stipule is an outgrowth typically borne on both sides (sometimes on just one side) of the base of a leafstalk (the petiole). They are primarily found among dicots and rare among monocots. Stipules are considered part of the anatomy ...
are absent. New plants often form easily from vegetative parts that fall off the parent plant.
Reproductive: The
inflorescence
In botany, an inflorescence is a group or cluster of flowers arranged on a plant's Plant stem, stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a mai ...
is usually terminal to lateral with many-flowered
thyrses of
cymes
In botany, an inflorescence is a group or cluster of flowers arranged on a plant's stem that is composed of a main branch or a system of branches. An inflorescence is categorized on the basis of the arrangement of flowers on a main axis ( ped ...
, less commonly spikes,
racemes
A raceme () or racemoid is an unbranched, indeterminate type of inflorescence bearing flowers having short floral stalks along the shoots that bear the flowers. The oldest flowers grow close to the base and new flowers are produced as the shoo ...
or
panicles
In botany, a panicle is a much-branched inflorescence. (softcover ). Some authors distinguish it from a compound spike inflorescence, by requiring that the flowers (and fruit) be pedicellate (having a single stem per flower). The branches of a p ...
, rarely few to single flowered and
axillary
Axillary means "related to the axilla (armpit)" or "related to the leaf axils".
"Axillary" may refer to: Biology
* Axillary artery
* Axillary border
* Axillary fascia
* Axillary feathers
* Axillary hairs
* Axillary lines
* Axillary lymph nodes ...
. The inflorescence is often many-branched and
bracteate
A bracteate (from the Latin ''bractea'', a thin piece of metal) is a flat, thin, single-sided gold medal worn as jewelry that was produced in Northern Europe predominantly during the Migration Period of the Germanic Iron Age (including the Ven ...
. The flower clusters are red, yellow, or white.
The flowers are often
apopetalous
Petals are modified leaves that form an inner whorl surrounding the reproductive parts of flowers. They are often brightly coloured or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''coroll ...
(separate
corolla segments), pentamerous (five-parted),
actinomorphic
Floral symmetry describes whether, and how, a flower, in particular its perianth, can be divided into two or more identical or mirror-image parts.
Uncommonly, flowers may have no axis of symmetry at all, typically because their parts are spirall ...
(radially symmetrical), except for the zygomorphic ''
Tylecodon grandiflorus
''Tylecodon'' is a genus of succulent plants in the family Crassulaceae, native to southern Africa.
Until the late 1970s all these plants were included in the genus ''Cotyledon (genus), Cotyledon'', but in 1978 Helmut Toelken of the Botanical Re ...
'', with one to two whorls of 4–20
sepals
A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106
Etymology
The term ''sepalum'' ...
that are usually as many as or twice as many as the number of
petals
Petals are modified leaves that form an inner whorl surrounding the reproductive parts of flowers. They are often brightly coloured or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''coroll ...
and two whorls of stamens, five in each whorl (i.e. as many as or twice the number of petals), with their filaments either free or fused to the petals at the base and sometimes unequal. Anthers are basifixed and open lengthwise. The flowers are bisexual, less commonly unisexual (more or less
dioecious
Dioecy ( ; ; adj. dioecious, ) is a characteristic of certain species that have distinct unisexual individuals, each producing either male or female gametes, either directly (in animals) or indirectly (in seed plants). Dioecious reproduction is ...
). Ovaries superior to partially inferior, with carpels equal to the number of petals, each forming a single locule, superior, free or almost so, basally with a small to conspicuous basal
nectary
Nectar is a viscous, sugar-rich liquid produced by plants in glands called nectaries, either within the flowers with which it attracts pollinating animals, or by extrafloral nectaries, which provide a nutrient source to animal mutualists, ...
scale, gradually tapering to a short to long
style
Style, or styles may refer to:
Film and television
* ''Style'' (2001 film), a Hindi film starring Sharman Joshi, Riya Sen, Sahil Khan and Shilpi Mudgal
* ''Style'' (2002 film), a Tamil drama film
* ''Style'' (2004 film), a Burmese film
* '' ...
with few to many ovules. The
fruit
In botany, a fruit is the seed-bearing structure in flowering plants (angiosperms) that is formed from the ovary after flowering.
Fruits are the means by which angiosperms disseminate their seeds. Edible fruits in particular have long propaga ...
is usually capsular with dehiscent follicles, opening along the carpal suture and many seeded. The
seeds
In botany, a seed is a plant structure containing an embryo and stored nutrients in a protective coat called a ''testa''. More generally, the term "seed" means anything that can be sown, which may include seed and husk or tuber. Seeds are the ...
are small (1.5–3 mm), smooth, elongate, papillate to longitudinally ridged, and generally brownish.
However, a number of genera (e.g.
Sempervivum
''Sempervivum'' () is a genus of about 40 species of flowering plants in the family (biology), family Crassulaceae, commonly known as houseleeks. Other common names include liveforever (the source of the taxonomical designation ''Sempervivum'', l ...
,
Aeonium
''Aeonium'', the tree houseleeks, is a genus of about 35 species of succulent, subtropical plants of the family Crassulaceae. Many species are popular in horticulture. The genus name comes from the ancient Greek αἰώνιος / aiōnios (ageles ...
) are
polymerous (3-32), have basally fused or partially fused corolla segments, where the petals may form a corolla tube of varying length (e.g. ''
Kalanchoe
''Kalanchoe'' ( ), (also called "kalanchöe" or "kalanchoë"), is a genus of about 125 species of tropical, succulent plants in the stonecrop family Crassulaceae, mainly native to Madagascar and tropical Africa. A ''Kalanchoe'' species was one ...
'', ''
Cotyledon
A cotyledon ( ; ; "a cavity, small cup, any cup-shaped hollow",
gen. (), ) is a "seed leaf" – a significant part of the embryo within the seed of a plant – and is formally defined as "the embryonic leaf in seed-bearing plants, one or mor ...
''), or have only a single whorl of 5 stamens (e.g. ''Crassula'', ''Tillaea''), while ''Sedum'' includes much of the morphological diversity within the family as a whole. Although the typical number of floral parts is four or five, a number of genera, such as ''
Sempervivum
''Sempervivum'' () is a genus of about 40 species of flowering plants in the family (biology), family Crassulaceae, commonly known as houseleeks. Other common names include liveforever (the source of the taxonomical designation ''Sempervivum'', l ...
'' and ''
Jovibarba'', demonstrate polymery (at least ten or greater parts).
Genome
The genome of ''
Kalanchoë fedtschenkoi'' has been sequenced as a model to study the evolution of Crassulacean acid metabolism (CAM).
Chromosome numbers are highly variable. The original base chromosome number is x=8, decreasing to 7 in Crassula. In Sedoideae, the base number increases to 9 in the Kalanchoe clade, but ''Kalanchoe'' have x=17 or 18 (or a multiple), and is probably of
polyploid
Polyploidy is a condition in which the biological cell, cells of an organism have more than two paired sets of (Homologous chromosome, homologous) chromosomes. Most species whose cells have Cell nucleus, nuclei (eukaryotes) are diploid, meaning ...
origin, derived from a
tetraploid
Polyploidy is a condition in which the cells of an organism have more than two paired sets of ( homologous) chromosomes. Most species whose cells have nuclei (eukaryotes) are diploid, meaning they have two complete sets of chromosomes, one fro ...
''Cotyledon'' like taxon. In the Telephium ''sensu'' Hart clade the base number has increased to 12 and higher. Of the subclades within Telephium, the first (Hylotelephium ''sensu'' Thiede & Eggli: ''Hylotelphium'', ''Orostachys'' and ''Sinocrassula'') has x=12, and of the Rhodiola clade ''Phedimus'' has x=16 and ''Umbilcus'' x=24, representing another episode of polyploidy. Within Sempervivum, ''Sedum'' series ''Rupestre'' (''Petrosedum'') has x=28. Within the Leucosedum, most taxa are
diploid
Ploidy () is the number of complete sets of chromosomes in a cell, and hence the number of possible alleles for autosomal and pseudoautosomal genes. Here ''sets of chromosomes'' refers to the number of maternal and paternal chromosome copies, ...
, with 2x=12, 14 but includes two subclades, one with x=6 or 7, the other x=6, but a few have 14 or 16. Acre includes a wide variety of chromosome numbers from x=6 to 270, and occasionally larger and displays widespread polyploidy. Aeonium includes some ''Sedum'' species with x=8, while the remaining taxa are x=18. The core of this clade is probably polyploid from an ancestor with x=8.
Phytochemistry
Crassulacean acid metabolism (CAM photosynthesis) is named after the family, because the pathway was first discovered in crassulacean plants. It is one of the few families that still has CAM as an active, photosynthetic pathway, and is unique in which all its members are known to possess CAM.
Taxonomy
Originally described by
Saint-Hilaire (1805) as Crassuleae, and therefore has his name as the
botanical authority
In botanical nomenclature, author citation is the way of citing the person or group of people who validly published a botanical name, i.e. who first published the name while fulfilling the formal requirements as specified by the ''International Cod ...
. Authority has also, at times, been given to
De Candolle
Augustin Pyramus (or Pyrame) de Candolle (, , ; 4 February 17789 September 1841) was a Swiss people, Swiss botany, botanist. René Louiche Desfontaines launched de Candolle's botanical career by recommending him at a herbarium. Within a couple ...
(DC), who first used the term "Crassulaceae" in 1815. He later placed the family among the
Dicotyledons
The dicotyledons, also known as dicots (or, more rarely, dicotyls), are one of the two groups into which all the flowering plants (angiosperms) were formerly divided. The name refers to one of the typical characteristics of the group: namely, ...
.
One of the most complete treatments was
Alwin Berger
Alwin Berger (28 August 1871 – 20 April 1931) was a German botanist best known for his contribution to the nomenclature of succulent plants, particularly agaves and cacti. Born in Germany he worked at the botanical gardens in Dresden and Fra ...
's revision in 1930. At that time the family comprised about 1,500 species, distributed over six subfamilies and 33 genera.
Circumscription
Circumscription may refer to:
* Circumscribed circle
* Circumscription (logic)
*Circumscription (taxonomy)
* Circumscription theory, a theory about the origins of the political state in the history of human evolution proposed by the American anthr ...
of the family has remained relatively stable, with the exception of the placement of the genus ''
Penthorum'' and ''
Tetracarpaea'', which has at times been placed either in their own
monogeneric
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unispe ...
family, Penthoraceae and Tetracarpaeaceae, or in the
Saxifragaceae
Saxifragaceae is a family of Herbaceous plant, herbaceous Perennial plant, perennial flowering plants, within the core eudicot Order (biology), order Saxifragales. The Taxonomy (biology), taxonomy of the family has been greatly revised and the ...
. When Penthorum and Tetracarpaea were separated from Crassulaceae, they became a natural monophyletic group. Some later authors, such as
Cronquist, included only 900 species. Thiede and Eggli (2007), in their treatment of the family, describe 34 genera with about 1,410 species. The size of the genera varies considerably, from ''Sedum'', the largest with 300–500 species, to the smallest, which are
monotypic
In biology, a monotypic taxon is a taxonomic group (taxon) that contains only one immediately subordinate taxon. A monotypic species is one that does not include subspecies or smaller, infraspecific taxa. In the case of genera, the term "unisp ...
. Estimates of the number of species has varied between 1500 (Berger 1930) and 900 (Cronquist 1981).
Molecular phylogenetics
Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...
has shown that morphological characters and chromosome numbers are so labile in the family, with rampant polyploidy and aneuploidy, that they cannot be used reliably to infer evolution, even at low taxonomic levels, with few exceptions. For instance ''Prometheum'' and ''Rosularia'' have been segregated from ''Sedum'' by their basic chromosome numbers.
Crassulaceae is a medium size
monophyletic
In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria:
# the grouping contains its own most recent co ...
grouping within the
core eudicots
The eudicots or eudicotyledons are flowering plants that have two seed leaves (cotyledons) upon germination. The term derives from ''dicotyledon'' (etymologically, ''eu'' = true; ''di'' = two; ''cotyledon'' = seed leaf). Historically, authors h ...
. Originally considered a primitive member of the
Rosidae
Under the International Code of Nomenclature for algae, fungi, and plants (ICN), Rosidae is a botanical name at the rank of subclass. Circumscription of the subclass will vary with the taxonomic system being used; the only requirement being th ...
, in the order
Saxifragales
Saxifragales is an order (biology), order of flowering plants in the Superrosids, superrosid clade of the eudicots. It contains 15 Families (biology), families and around 100 genera, with nearly 2,500 species. Well-known and economically import ...
, it is now placed, with that order as a
superrosid
The superrosids are members of a large clade (monophyletic group) of flowering plants, containing more than 88,000 species, and thus more than a quarter of all angiosperms.
The clade is divided into 18 orders as defined in APG IV system. These o ...
under the classification system of the
Angiosperm Phylogeny Group
The Angiosperm Phylogeny Group (APG) is an informal international group of systematic botanists who collaborate to establish a consensus on the taxonomy of flowering plants (angiosperms) that reflects new knowledge about plant relationships disc ...
. There, the Saxifragales are a
sister group
In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree.
Definition
The expression is most easily illustrated by a cladogram:
Taxon A and ...
to the
rosids
The rosids are members of a large clade (monophyly, monophyletic group) of flowering plants, containing about 70,000 species, more than a quarter of all angiosperms.
The clade is divided into 16 to 20 Order (biology), orders, depending upon Circu ...
. Classification within the family is difficult and complex because many of the species hybridize readily, both in the wild and in cultivation, and the family is
morphologically,
cytologically and geographically diverse. As a result, generic boundaries have been considered unclear with frequent intergradation of characteristics between
taxa
In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...
, which may represent recurrent adaptation to xeric habitats.
Phylogeny
Crassulaceae has been considered a part of the order
Saxifragales
Saxifragales is an order (biology), order of flowering plants in the Superrosids, superrosid clade of the eudicots. It contains 15 Families (biology), families and around 100 genera, with nearly 2,500 species. Well-known and economically import ...
by most modern authors, including
Cronquist (1981),
Takhtajan
Armen Leonovich Takhtajan or Takhtajian (; surname also transliterated Takhtadjan, Takhtadzhi︠a︡n or Takhtadzhian, pronounced takh-tuh-JAHN; 10 June 1910 – 13 November 2009), was a Soviet-Armenian botanist, one of the most important figu ...
(1987), and
Thorne (1992), based on
phenotypic
In genetics, the phenotype () is the set of observable characteristics or traits of an organism. The term covers the organism's morphology (physical form and structure), its developmental processes, its biochemical and physiological propert ...
features, but subsequently confirmed by molecular methods. The place of Crassulaceae within Saxifragales has varied over time, as molecular data accumulates. The number of families within Saxifragales varies depending on the delimitation of individual families. Here, 14 families are shown in a
cladogram
A cladogram (from Greek language, Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an Phylogenetic tree, evolutionary tree because it does not s ...
, according to the
Angiosperm Phylogeny Website
The Angiosperm Phylogeny Website (or APweb) is a website that presents up-to-date research on the phylogeny and taxonomy of flowering plants (angiosperms) in what is intended to be a user-friendly way.
The site is hosted by the Missouri Botanical ...
, situating Crassulaceae as
sister
A sister is a woman or a girl who shares parents or a parent with another individual; a female sibling. The male counterpart is a brother. Although the term typically refers to a familial relationship, it is sometimes used endearingly to ref ...
to the
Haloragaceae
Haloragaceae (the watermilfoil family) is a eudicot flowering plant family in the order Saxifragales, based on the phylogenetic APG system. In the Cronquist system, it was included in the order Haloragales.
Description
The Haloragaceae ...
''sensu lato'', and thus forming one of two subclades of the core Saxifragales.
Biogeography and evolution
Crassulaceae evolved approximately 100–60 million years ago in southern Africa with the two most basal phylogenetic branches (Crassula, Kalanchoe) representing the predominantly southern African members. Other sources suggest that Crassulaceae evolved approximately 70 million years ago together with Haloragaceae ''sensu lato'' (
Penthoraceae
''Penthorum'' is a genus of plants in the order Saxifragales. They are erect herbaceous perennials about half a meter tall. The genus consists of two species, one from east Asia and one from eastern North America. It is variously classified i ...
,
Haloragaceae
Haloragaceae (the watermilfoil family) is a eudicot flowering plant family in the order Saxifragales, based on the phylogenetic APG system. In the Cronquist system, it was included in the order Haloragales.
Description
The Haloragaceae ...
). The family is considered to have had a gradual evolution, with a
basal split between Crassuloideae and the rest of the family (Kalanchoideae, Sempervivoideae). The Sempervivoideae subsequently dispersed north to the Mediterranean region, and from there to Eastern Europe and Asia (Sempervivum and Leucosedum clades), with multiple groups spreading over the three continents of the Northern Hemisphere. Two lineages from the European Crassulaceae eventually dispersed to North America and underwent subsequent diversification. The Aeonium clade dispersed from northern Africa to adjacent Macaronesia.
Distinct centers of
speciation
Speciation is the evolutionary process by which populations evolve to become distinct species. The biologist Orator F. Cook coined the term in 1906 for cladogenesis, the splitting of lineages, as opposed to anagenesis, phyletic evolution within ...
developed in Macaronesia (Aeonium clade), Mexico (''Sedum'' and Echeverioideae in clade 7), and southeastern Asia (''Sedum sarmentosum'', and ''S. morissonensis'' in Acre clade). On arrival in the Northern hemisphere the Sempervivoideae reached its greatest diversity. Conversely, few representatives of the Crassulaceae occur in South America and Australia. ''Sedum'' species are found in most of these regions, generally grouped with genera endemic to that region. For instance the North African ''S. jaccardianum'' and ''S. modestum'' (Aeonium) are a sister group to the endemic Macaronesian species in that clade.
The Macaronesian archipelago appears to have been reached by Crassulaceae at least three times. Once by the ancestor
of ''Aeonium'' and ''Monanthes'', most likely from the Western Mediterranean region, with the closest extant relatives of these two genera (''Sedum caeruleum'', ''S. pubescens''), coming from this region (Aeonium clade). The second migration was by an ancestor of a clade of three ''Sedum'' species (''S. nudum'', ''S. lancerotense'' and ''S. fusiforme'' (Acre clade)), which appear to have originated in Mexico. The third occurrence likely involved the ancestor of a lineage within the genus ''Umbilicus'' (Rhodiola clade). The Macronesian flora include three genera from the Sempervivoideae, ''Aeonium'', ''Aichryson'' and ''Monanthes'' (Aeonium clade), together with several ''Sedum'' spp. and one species of ''Umbilicus'' (Rhodiola). North America was reached at least twice, once by an ancestor of ''Parvisedum'' and ''Dudleya'', and once by a subclade of Acre. For a mapping of morphological features and biogeography on the phylogenetic tree, see Fig. 3.
Chromosome numbers have played a limited role in elucidating evolution, but suggest a core of x=8, with subsequent polyploidy. For a mapping of chromosome numbers on the phylogenetic tree, see Fig. 4.
Subdivision
History
When
Carl Linnaeus
Carl Linnaeus (23 May 1707 – 10 January 1778), also known after ennoblement in 1761 as Carl von Linné,#Blunt, Blunt (2004), p. 171. was a Swedish biologist and physician who formalised binomial nomenclature, the modern system of naming o ...
published his ''
Species Plantarum
' (Latin for "The Species of Plants") is a book by Carl Linnaeus, originally published in 1753, which lists every species of plant known at the time, classified into genus, genera. It is the first work to consistently apply binomial nomenclature ...
'' in 1753 only a few genera, included in the modern
circumscription
Circumscription may refer to:
* Circumscribed circle
* Circumscription (logic)
*Circumscription (taxonomy)
* Circumscription theory, a theory about the origins of the political state in the history of human evolution proposed by the American anthr ...
of Crassulaceae were described; the
type genus
In biological taxonomy, the type genus (''genus typica'') is the genus which defines a biological family and the root of the family name.
Zoological nomenclature
According to the International Code of Zoological Nomenclature, "The name-bearin ...
''
Crassula
''Crassula'' is a genus of succulent plants containing about 200 accepted species, including the popular jade plant (''Crassula ovata''). They are members of the stonecrop family (Crassulaceae) and are native to many parts of the globe, but culti ...
'' (10 species), ''
Tillaea'' (3), ''
Cotyledon
A cotyledon ( ; ; "a cavity, small cup, any cup-shaped hollow",
gen. (), ) is a "seed leaf" – a significant part of the embryo within the seed of a plant – and is formally defined as "the embryonic leaf in seed-bearing plants, one or mor ...
'' (6), ''
Sempervivum
''Sempervivum'' () is a genus of about 40 species of flowering plants in the family (biology), family Crassulaceae, commonly known as houseleeks. Other common names include liveforever (the source of the taxonomical designation ''Sempervivum'', l ...
'' (6), ''
Rhodiola
''Rhodiola'' is a genus of perennial plants in the family Crassulaceae that resemble '' Sedum'' and other members of the family. Like sedums, ''Rhodiola'' species are often called stonecrops. Some authors merge ''Rhodiola'' into ''Sedum''.
' ...
'' (1) and ''Sedum'' (15). By 1777, ''Rhodiola'' had been submerged into ''Sedum'', only to be separated again in the twentieth century.
While the family can fairly easily be recognised, identifying its constituent genera has been far more problematic. For an extensive history of subfamily Sedoideae, see . Saint-Hilaire's original description in 1805 included seven genera, as did De Candolle (1815). In a much more extensive treatment in 1828, he divided the Crassulaceae into the two groups, Isostemonae and Diplostemonae (i.e. haplostemony vs. obdiplostemony) on the basis of the number of staminal whorls. The former corresponded to the modern Crassuloideae.
Two lineages, six subfamilies, and 33 genera of Crassulaceae were described by Berger in 1930:
Lineages, subfamilies, biogeography, No. genera, ''type genus'' (No. species in genus)
* Crassula (Southern hemisphere)
** Crassuloideae S Africa 5 ''Crassula'' (300)
*** (''
Crassula
''Crassula'' is a genus of succulent plants containing about 200 accepted species, including the popular jade plant (''Crassula ovata''). They are members of the stonecrop family (Crassulaceae) and are native to many parts of the globe, but culti ...
'', ''Dinacria'', ''Rochea'', ''Vauanthes'', ''Pagella'')
** Kalanchiodeae S Africa, Madagascar 3 ''Kalanchoe'' (200)
*** (''
Kalanchöe'', ''
Bryophyllum
''Bryophyllum'' (from the Greek ''bryon/bryein'' = sprout, ''phyllon'' = leaf) is a group of plant species of the family (biology), family Crassulaceae native to Madagascar. It is a Section (botany), section or subgenus within the genus ''Kalan ...
'', ''Kitchingia'')
** Cotyledonoideae S Africa, Mediterranean 6 ''Cotyledon'' (30)
*** (''
Cotyledon
A cotyledon ( ; ; "a cavity, small cup, any cup-shaped hollow",
gen. (), ) is a "seed leaf" – a significant part of the embryo within the seed of a plant – and is formally defined as "the embryonic leaf in seed-bearing plants, one or mor ...
'', ''
Adromischus
''Adromischus'' is a genus of flowering plants. They are easily-propagated, leaf succulents from the family Crassulaceae, which are endemism, endemic to southern Africa. The name comes from the ancient Greek ''adros'' (=thick) and ''mischos'' (= ...
'', ''
Umbilicus
Umbilicus may refer to:
*The navel or belly button
*Umbilicus (mollusc), a feature of gastropod, Nautilus and Ammonite shell anatomy
*Umbilicus (plant), ''Umbilicus'' (plant), a genus of over ninety species of perennial flowering plants
*Umbilicus ...
'', ''
Chiastophyllum'', ''Pistorina'', ''Mucizonia'')
* Sedum (Northern hemisphere)
** Echeveroideae Mexico 5 ''Echeveria'' (150)
*** (''
Echeveria
''Echeveria'' is a large genus of flowering plants in the family (biology), family Crassulaceae, native plant, native to semi-desert areas of Central America, Mexico and northwestern South America.
Description
Echeveria plants are evergreen. Flo ...
'', ''
Villadia'', ''Altamiranoa'', ''
Pachyphytum
''Pachyphytum'' is a small genus of Succulent plant, succulents in the Sedum, stonecrop family, Crassulaceae, native to Mexico, where species can be found growing at elevations from above sea level. The generic name comes from the ancient Greek ...
'', ''
Lenophyllum'')
** Sempervivoideae Mediterranea, Macaronesia 5 ''Sempervivum'' (25)
*** (''
Sempervivum
''Sempervivum'' () is a genus of about 40 species of flowering plants in the family (biology), family Crassulaceae, commonly known as houseleeks. Other common names include liveforever (the source of the taxonomical designation ''Sempervivum'', l ...
'', ''
Aeonium
''Aeonium'', the tree houseleeks, is a genus of about 35 species of succulent, subtropical plants of the family Crassulaceae. Many species are popular in horticulture. The genus name comes from the ancient Greek αἰώνιος / aiōnios (ageles ...
'', ''Greenovia'', ''
Monanthes
''Monanthes'' is a genus of small, succulent, subtropical plants of the family Crassulaceae. Most species in the genus are endemic to the Canary Islands, with one species also endemic to the Savage Islands and another to the High Atlas mountains ...
'', ''
Aichryson
''Aichryson'' is a genus of 16 species of succulent, subtropical plants, native to the Canary Islands, Azores, and Madeira.
The species of ''Aichryson'' are not frost-resistant. They are related to ''Sempervivum, Jovibarba, Greenovia, Aeonium' ...
'')
** Sedoideae N hemisphere, S America, N & E Africa 11 ''Sedum'' (500)
*** (''
Sedum
''Sedum'' is a large genus of flowering plants in the family Crassulaceae, members of which are commonly known as stonecrops. The genus has been described as containing up to 600 species, subsequently reduced to 400–500. They are leaf succule ...
'' (since including ''Diamorpha''), ''
Rosularia'', ''
Orostachys
''Orostachys'' is a genus of the succulent family Crassulaceae (stonecrop family) that contains about 15 species. It is a biennial herb growing in China, Japan, Kazakhstan, Korea, Mongolia, Russia. Eight species occur in China.
Description
''Or ...
'', ''
Pseudosedum
''Pseudosedum'' is a genus of flowering plants in the family Crassulaceae native to Central Asia and Siberia. Species
Species in the genus include:
* '' Pseudosedum acutisepalum'' C.-A.Jansson
* '' Pseudosedum affine'' (Schrenk) A.Berger
* '' Pse ...
'', ''
Hypagophytum'', ''
Afrovivella'', ''Sempervivella'', ''Sinocrassula'')
Each of these contained one of the largest genera. Though various revisions since have proposed simpler schemes, such as Borisova (1939, revised 1969). Berger's classification has proven practical and been the most widely used, although some of the subfamilies are polyphyletic. Berger's classification depended on biogeography and a number of morphological characteristics (primarily the number and arrangement of floral parts (haplostemonous androecia, polymery), the degree of
sympetaly, and
phyllotaxis
In botany, phyllotaxis () or phyllotaxy is the arrangement of leaf, leaves on a plant stem. Phyllotactic spirals form a distinctive class of patterns in nature.
Leaf arrangement
The basic leaf#Arrangement on the stem, arrangements of leaves ...
) which are now recognized as being of limited value due to extensive
homoplasy
Homoplasy, in biology and phylogenetics, is the term used to describe a feature that has been gained or lost independently in separate lineages over the course of evolution. This is different from homology, which is the term used to characterize ...
, having evolved independently many times, and hence provides little useful information, only two of the subfamilies proving
monophyletic
In biological cladistics for the classification of organisms, monophyly is the condition of a taxonomic grouping being a clade – that is, a grouping of organisms which meets these criteria:
# the grouping contains its own most recent co ...
. Berger used sympetaly to define the group of Kalanchiodeae, Cotyledonoideae and Echeveroideae, but it also occurs in taxa within Crassuloideae and Sedoideae. Berger also placed all species with polymery into his Sempervivoideae, but it occurs in two different clades, Sempervivum and Aeonium. Although five of his six subfamilies appeared to be morphologically and geographically defined, the Sedoideae were problematic, being an artificial construction containing all
taxa
In biology, a taxon (back-formation from ''taxonomy''; : taxa) is a group of one or more populations of an organism or organisms seen by taxonomists to form a unit. Although neither is required, a taxon is usually known by a particular name and ...
which could not be fitted into the other subfamilies (
catch-all).
Sedoideae contained three centres of diversity, East Asia, the Mediterranean region and North America, with the greatest in E. Asia. Only a few taxa, such as ''Rhodiola'' and ''Hylotelephium'', occurring in all three regions. About 120 species were found in Europe and adjacent parts of North Africa and West Asia, and 400 in Eastern and central Asia.
Within Sedoideae, the large cosmopolitan typical genus ''Sedum'' (ca. 500 species), accounts for much of these issues, together with several smaller genera. ''Sedum'' refers to herbaceous, predominantly perennial species with alternate and entire leaves, a single subaxial
hydathode
A hydathode is a type of pore, commonly found in vascular plants, that secretes water through pores in the epidermis or leaf margin, typically at the tip of a marginal tooth or serration. Hydathodes occur in the leaves of submerged aquatic plant ...
and pentamerous obdiplostemous flowers with free petals. Most systematic treatments of the genus have resulted in conflicting classifications and evolutionary relationships within the Sedoideae. Attempts to resolve this have followed two opposing positions,
lumping and splitting
Lumpers and splitters are opposing factions in any academic discipline that has to place individual examples into rigorously defined categories. The lumper–splitter problem occurs when there is the desire to create classifications and assign ...
. Either accepting one artificial large
catch-all polyphyletic
A polyphyletic group is an assemblage that includes organisms with mixed evolutionary origin but does not include their most recent common ancestor. The term is often applied to groups that share similar features known as Homoplasy, homoplasies ...
genus, ''
sensu lato
''Sensu'' is a Latin word meaning "in the sense of". It is used in a number of fields including biology, geology, linguistics, semiotics, and law. Commonly it refers to how strictly or loosely an expression is used in describing any particular co ...
'' (''Sedum s.l.''), or splitting it into many smaller genera, ''sensu stricto'' (''Sedum s.l.''). In the 1930s, Berger represented the splitting school of thought segregating genera such as ''
Orostachys
''Orostachys'' is a genus of the succulent family Crassulaceae (stonecrop family) that contains about 15 species. It is a biennial herb growing in China, Japan, Kazakhstan, Korea, Mongolia, Russia. Eight species occur in China.
Description
''Or ...
'', ''
Rosularia'', ''
Pseudosedum
''Pseudosedum'' is a genus of flowering plants in the family Crassulaceae native to Central Asia and Siberia. Species
Species in the genus include:
* '' Pseudosedum acutisepalum'' C.-A.Jansson
* '' Pseudosedum affine'' (Schrenk) A.Berger
* '' Pse ...
'' and ''
Sempervivella''. In contrast, Fröderströmm favoured retaining a broader construct of ''Sedum'', recognising only ''Pseudosedum''. In more recent times Ohba (1978) proposed the narrower view, segregating ''
Rhodiola
''Rhodiola'' is a genus of perennial plants in the family Crassulaceae that resemble '' Sedum'' and other members of the family. Like sedums, ''Rhodiola'' species are often called stonecrops. Some authors merge ''Rhodiola'' into ''Sedum''.
' ...
'', ''
Hylotelephium
''Hylotelephium'' is a genus of flowering plants in the stonecrop family Crassulaceae. It includes about 33 species distributed in Asia, Europe, and North America.
Species in the genus, formerly included in ''Sedum'', are popular garden plants, ...
'' and ''
Prometheum'', among other genera. Ohba then subdivided the old world taxa of his now reduced ''Sedum'' into five subgenera:
* subgenus ''Aizoon''
* subgenus ''Balfouria''
* subgenus ''Spathulata''
* subgenus ''Sedum''
* subgenus ''Telmissa''
Grulich (1984) continued this process, proposing ''
Aizopsis'' (subgenus ''Aizoon''), ''
Asterosedum'' (subgenus ''Spathulata''), ''
Petrosedum'' (subgenus ''Sedum'' series ''Rupestria'') and ''
Oreosedum'' (subgenus ''Sedum'' series ''Alba'') as separate genera. As many as 32 segregate genera have been published, and most Eurasian crassulacean species were originally included in ''Sedum'', but subsequently segregated (''see''
Sempervivoideae
Sempervivoideae is the largest of three subfamilies in the Saxifragales family Crassulaceae, with about 20–30 genera with succulent leaves. Unlike the two smaller subfamilies, it is distributed in temperate climates. The largest genus in this s ...
).
Subsequently, various revisions have proposed fewer subfamilies.
Takhtajan
Armen Leonovich Takhtajan or Takhtajian (; surname also transliterated Takhtadjan, Takhtadzhi︠a︡n or Takhtadzhian, pronounced takh-tuh-JAHN; 10 June 1910 – 13 November 2009), was a Soviet-Armenian botanist, one of the most important figu ...
(1987) initially submerged Sempervivoideae in Sedoideae and Cotyledonoideae in Kalanchiodeae to produce four, but later (1997) only three, Crassuloideae, Kalanchoideae and Sedoideae.
Thorne (1992) also proposed three (Sedoidea, Cotyledonoidea, Crassuloidea), and then two (2000), Crassuloideae and Sempervivoideae.
Molecular phylogenetics
Prior to the use of molecular methods of classification, attempts to replace Berger's system were largely unsuccessful. Subsequently, Hart and colleagues (1995) proposed two subfamilies, based on
molecular phylogenetic
Molecular phylogenetics () is the branch of phylogeny that analyzes genetic, hereditary molecular differences, predominantly in DNA sequences, to gain information on an organism's evolutionary relationships. From these analyses, it is possible to ...
data with
chloroplast DNA
Chloroplast DNA (cpDNA), also known as plastid DNA (ptDNA) is the DNA located in chloroplasts, which are photosynthetic organelles located within the cells of some eukaryotic organisms. Chloroplasts, like other types of plastid, contain a genome s ...
, based on 49 species in 26 genera, which identified seven clades, named for constituent genera or species. Hart utilized a hierarchical system of subfamilies, tribes and subtribes, based on molecular, geographical and morphological criteria, including
embryology
Embryology (from Ancient Greek, Greek ἔμβρυον, ''embryon'', "the unborn, embryo"; and -λογία, ''-logy, -logia'') is the branch of animal biology that studies the Prenatal development (biology), prenatal development of gametes (sex ...
,
pollen
Pollen is a powdery substance produced by most types of flowers of seed plants for the purpose of sexual reproduction. It consists of pollen grains (highly reduced Gametophyte#Heterospory, microgametophytes), which produce male gametes (sperm ...
morphology and
phytochemistry
Phytochemistry is the study of phytochemicals, which are chemicals derived from plants. Phytochemists strive to describe the structures of the large number of secondary metabolites found in plants, the functions of these compounds in human and ...
.
* Subfamily Crassuloideae
Berger Type: ''Crassula'' 2 South African genera (250 species)
* Subfamily Sedoideae
Berger Type: ''Sedum''
** Tribe Kalanchoeae
't Hart Type: ''Kalanchoe'' 5 S African genera (250 spp.)
** Tribe Sedeae
't Hart Type: ''Sedum''
*** Subtribe Telephiinae
't Hart Type: ''Hylotelephium'' 8 Asian genera (150 spp.)
*** Subtribe Sedinae
't Hart Type: ''Sedum'' 18 Northern hemisphere genera (700 spp.)
The basal split at subfamily level, separates the
haplostemonous
This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary ...
(single series of stamens, equal in number to petals) African Crassuloideae with opposite leaves, from the Sedeae without these characteristics (
obdiplostemonous, two whorls of stamens, twice as many as petals).
These clades were (1–7):
# Crassula/Crassuloideae, the
basal divergence, corresponds to Berger's subfamily of that name and are haplostemonous, but this feature is homoplasious. Confined to southern Africa, except for aquatic species, which are cosmopolitan.
# Kalanchoe/Kalanchoeae, the second divergence, corresponds to Berger's Kalanchoideae (''Kalanchoe'', ''Bryophyllum'', ''Kitchingia'') and the 2 S. African members of Cotyledonoideae (''Adromischus'', ''Cotyledon''), together with ''
Tylecodon
''Tylecodon'' is a genus of succulent plants in the family Crassulaceae, native to southern Africa.
Until the late 1970s all these plants were included in the genus ''Cotyledon'', but in 1978 Helmut Toelken of the Botanical Research Institute, ...
'' which was segregated from ''Cotyledon'' in 1978. It was characterized by 4- or 5-merous flowers,
connate petals and seeds, together with
leaves
A leaf (: leaves) is a principal appendage of the stem of a vascular plant, usually borne laterally above ground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", while the leaves, stem, ...
that are flat, crenate or dentate (toothed), often petiolate and decussate. Chromosome number x=9. Within the clade, ''Adromischus'' forms the basal divergence, followed by ''Cotyledon''/''Tylecodon'' as sister to ''Kalanchoe''.
# Telephium/Telephiinae include members of Cotyledonoideae (''Umbilicus''), together with some Sedoideae genera (including ''Hylotelephium'') and two of Ohba's five subgenera of ''Sedum'' (''Aizoon'' and ''Spathulata'') and are usually obdiplostemonous, 5-merous flowers with free petals, flat and often crenate or dentate leaves ("flat leaved Asian ''Sedum''") and have
tubers
Tubers are a type of enlarged structure that plants use as storage organs for nutrients, derived from stems or roots. Tubers help plants perennate (survive winter or dry months), provide energy and nutrients, and are a means of asexual reprod ...
, tuberous roots or woody or thickened
rhizomes
In botany and dendrology, a rhizome ( ) is a modified subterranean plant stem that sends out roots and shoots from its nodes. Rhizomes are also called creeping rootstalks or just rootstalks. Rhizomes develop from axillary buds and grow hori ...
(
monopodial
Vascular plants with monopodial growth habits grow upward from a single point. They add leaves to the apex each year and the stem grows longer accordingly. The word ''Monopodial'' is derived from Greek language, Greek '', ''one'' and '', "foot", in ...
or sympodial). In this respect many species share leaf features with the Kalanchoeae and Hart considered that the Telephiinae "bridge the gap" between the African Kalanchoeae and the Northern hemisphere Sedinae. Distribution predominantly East Asia, with ''Umbilicus'' being Mediterranean.
# Sempervivum includes the montane/alpine Eurasian ''Sempervivum'', its nominative genus, together with ''Sedum'' from the same region, including ''Sedum'' series ''Rupestria''. ''Sempervivum'' is closely related to ''Jovibarba'', which some authors place within the former genus.
# Leucosedum, i.e. "White Sedum", from ''Sedum album'', is polygeneric and includes additional Cotyledonoideae and Eurasian Sedoideae, including ''
Sedum album
''Sedum album'', the white stonecrop, is a flowering plant of the genus ''Sedum'' in the family Crassulaceae. It is found in the northern temperate regions of the world, often growing in crevices or free-draining rocky soil. As a long-day plant ...
'' and other species of ''Sedum'' subgenus ''Gormania''. The other genera are thought to have evolved from the Sedum lineage in this clade, including ''Dudleya'' and ''Sedella'' (N America) and ''Rosularia'', ''Prometheum'' and ''Pistorina'' (Eurasia). This grouping of 5–7 genera accounts for about 200 species. Some ''Sedum'' subgenus ''Sedum'' species also place here. Leucosedum species are found throughout the arid southwest United States and Mexico, as well as Eurasia.
# Aeonium is predominantly Macaronesian Sempervivoideae (''Aeonium'', ''Aichryson'', ''Greenovia'' and ''Monanthes''), from a N African ancestor, and N. African ''Sedum''. Berger grouped the genera of that subfamily on the basis of polymerous flowers, but this is not restricted to this clade.
# Acre, with about 7 genera and 500 species is the most taxon rich clade in the Crasulaceae. It includes the American subfamily Echeveroideae and ''Sedum'' from Asia, Europe and Macaronesia, Mexico and Africa, including ''
Sedum acre
''Sedum acre'', commonly known as the goldmoss stonecrop, mossy stonecrop, goldmoss sedum, biting stonecrop, and wallpepper, is a perennial flowering plant in the family Crassulaceae. It is native to Europe, northern and western Asia and North A ...
'' and ''Sedum'' subgenus ''Sedum''. The strong representation of ''Sedum'' in this large clade accounts for it comprising a third of the diversity of the family. Two subclades consist of the N American and Macaronesian taxa, the other Eurasian.
The last subtribe, the Sedinae, represents the last four clades (4–7) and contained half of the genera and species of Crassulaceae, including ''Sedum'', which is represented in all four clades, and the bulk of clades 5 and 7. In addition to ''Sedum'', 16 other genera are recognised. Aeonium is basal divergence, followed by Sempervivum, with Leucosedum and Acre as sister groups. The Sedinae were very diverse, making phenotypic circumscription impossible. A similar problem exists for each of its subclades. Given the realisation that ''Sedum'' ''s.l.'' was a highly artificial construction, there was support for reducing it by describing a number of segregate genera. Ohba (1995) proposed that ''Sedum'' ''s.s.'' should be restricted to clade 7, or at most clades 5–7, continuing some of the premolecular work in this direction, newly describing a number of Asian genera in addition to this reduced ''Sedum''.:
* ''
Hylotelephium
''Hylotelephium'' is a genus of flowering plants in the stonecrop family Crassulaceae. It includes about 33 species distributed in Asia, Europe, and North America.
Species in the genus, formerly included in ''Sedum'', are popular garden plants, ...
''
* ''
Orostachys
''Orostachys'' is a genus of the succulent family Crassulaceae (stonecrop family) that contains about 15 species. It is a biennial herb growing in China, Japan, Kazakhstan, Korea, Mongolia, Russia. Eight species occur in China.
Description
''Or ...
''
* ''
Aizopsis''
* ''
Phedimus
''Phedimus'' is a genus of the succulent family Crassulaceae (stonecrop family), with about 18 species, distributed in eastern Europe and Asia. The genus is described with two subgenera, but one of these is also recognized as a separate genus, '' ...
''
* ''
Rhodiola
''Rhodiola'' is a genus of perennial plants in the family Crassulaceae that resemble '' Sedum'' and other members of the family. Like sedums, ''Rhodiola'' species are often called stonecrops. Some authors merge ''Rhodiola'' into ''Sedum''.
' ...
''
* ''
Prometheum''
* ''
Rosularia''
* ''
Balfouria''
* ''
Sinocrassula
''Sinocrassula'' is a genus of succulent, subtropical plants of the family Crassulaceae.
The name "Sinocrassula" means "Chinese crassula". They come from the province Yunnan in the south of China, and also from the north of Burma. They grow at a ...
''
* ''
Meterostachys''
* ''
Pseudosedum
''Pseudosedum'' is a genus of flowering plants in the family Crassulaceae native to Central Asia and Siberia. Species
Species in the genus include:
* '' Pseudosedum acutisepalum'' C.-A.Jansson
* '' Pseudosedum affine'' (Schrenk) A.Berger
* '' Pse ...
''
The general phylogenetic topology described by 't Hart et al. (1995) was confirmed in a larger study of 112 species of Crassulaceae sampled from 33 genera, and all six recognized subfamilies, using the chloroplast gene ''
matK''. The Telephium clade, which had only been weakly supported, was seen as probably containing several subclades. A similar conclusion was seen in a further but more focussed study of East Asian Sedoideae that examined the
internal transcribed spacer
Internal transcribed spacer (ITS) is the spacer DNA situated between the small-subunit ribosomal RNA (rRNA) and large-subunit rRNA genes in the chromosome or the corresponding transcribed region in the polycistronic rRNA precursor transcript.
...
(ITS) region of nuclear
ribosomes
Ribosomes () are macromolecular machines, found within all cells, that perform biological protein synthesis (messenger RNA translation). Ribosomes link amino acids together in the order specified by the codons of messenger RNA molecules to fo ...
of 74 taxa. This region includes about 300 species of Sedoideae, and most genera segregated from ''Sedum''. However the Telephium clade of Ham was recognised as actually consisting of four separate clades, of which the two largest were named Hylotelephium and Rhodiola. The former are distinguished by being autumn flowering, while the remaining Sedeae bloom in spring and early summer. This analysis also confirmed the separate identity of most of the genera previously segregated from ''Sedum''. A second ITS study of 69 taxa in ten Asian genera resolved Telephium into just these two larger clades.
Hart's taxonomic classification was revised by Thiede and Eggli (2007) to define three molecularly defined subfamilies, corresponding to the major
clades
In biology, a clade (), also known as a monophyletic group or natural group, is a group of organisms that is composed of a common ancestor and all of its descendants. Clades are the fundamental unit of cladistics, a modern approach to taxonomy ...
, Crassuloideae, Kalanchoöideae and Sempervivoideae, and 34 genera. Although some authors prefer the older term Sedoideae for Sempervivoideae, Sempervivoideae has taxonomic priority. The earliest branching subfamily is the Crassuloideae (2 genera), followed by the Kalanchoöideae (4 genera). Both of these represent the genera of southern Africa. The remaining six clades are
segregated into the five tribes of the large temperate climate subfamily Sempervivoideae, with about thirty genera. These are Telephiae, Umbilicicae, Semperviveae, Aeonieae and Sedeae. Sedeae is the largest of these and contains two
sister
A sister is a woman or a girl who shares parents or a parent with another individual; a female sibling. The male counterpart is a brother. Although the term typically refers to a familial relationship, it is sometimes used endearingly to ref ...
clades, Leucosedum and Acre. The Sempervivoideae contain many familiar horticultural plants, such as ''Sedum''. The phylogenetic relationships between the subfamilies are shown in the cladogram.
Subfamilies
= Crassuloideae Burnett
=
Crassuloideae is the smallest subfamily, representing a single monophyletic clade (Crassula), defined by
haplostemonous
This glossary of botanical terms is a list of definitions of terms and concepts relevant to botany and plants in general. Terms of plant morphology are included here as well as at the more specific Glossary of plant morphology and Glossary ...
androecia (characterized by a single
whorl
A whorl ( or ) is an individual circle, oval, volution or equivalent in a whorled pattern, which consists of a spiral or multiple concentric objects (including circles, ovals and arcs).
In nature
File:Photograph and axial plane floral diagra ...
of
stamens
The stamen (: stamina or stamens) is a part consisting of the male reproductive organs of a flower. Collectively, the stamens form the androecium., p. 10
Morphology and terminology
A stamen typically consists of a stalk called the filamen ...
, the number of which equals the number of
sepals
A sepal () is a part of the flower of angiosperms (flowering plants). Usually green, sepals typically function as protection for the flower in bud, and often as support for the petals when in bloom., p. 106
Etymology
The term ''sepalum'' ...
,
petals
Petals are modified leaves that form an inner whorl surrounding the reproductive parts of flowers. They are often brightly coloured or unusually shaped to attract pollinators. All of the petals of a flower are collectively known as the ''coroll ...
and
carpels
Gynoecium (; ; : gynoecia) is most commonly used as a collective term for the parts of a flower that produce ovules and ultimately develop into the fruit and seeds. The gynoecium is the innermost whorl of a flower; it consists of (one or more) ...
, and alternating with the petals). Although cosmopolitan in distribution, the center of diversity is southern Africa, with only the aquatic species being found more widely. It consists of two genera and about 250–300 species (Berger's other four genera (''Dinacria'', ''Pagella'', ''Rochea'', ''Vauanthes'') having been subsumed into a larger ''Crassula'' ''s.l.''). Crassula is morphologically diverse and up to 20 sections based on phenotypic features have been described. One of these, ''Tillaea'', has at times been considered a separate genus. ''Hypagophytum'' is a monotypic genus, alternatively considered under
Sempervivoideae
Sempervivoideae is the largest of three subfamilies in the Saxifragales family Crassulaceae, with about 20–30 genera with succulent leaves. Unlike the two smaller subfamilies, it is distributed in temperate climates. The largest genus in this s ...
.
* ''
Crassula
''Crassula'' is a genus of succulent plants containing about 200 accepted species, including the popular jade plant (''Crassula ovata''). They are members of the stonecrop family (Crassulaceae) and are native to many parts of the globe, but culti ...
''
L. (including ''
Tillaea''
L.) c. 200 spp.
* ''
Hypagophytum''
A.Berger 1 sp.
= Kalanchoöideae A.Berger
=
Kalanchoöideae is the next smallest subfamily, characterised by flower parts in fours. It represents Berger's Kalanchiodeae and Cotyledonoideae, in part. It is distributed in Madagascar and tropical Africa, with four genera and about between 130–240 species. It is characterised by fused corollas, chromosome number x=9 and mostly southern African distribution. The boundaries between ''Kalanchoe'', ''Bryophyllum'' and ''Kitchingia'' have remained unclear, and the latter two genera are more commonly treated as sections of ''Kalanchoe'':
* ''
Adromischus
''Adromischus'' is a genus of flowering plants. They are easily-propagated, leaf succulents from the family Crassulaceae, which are endemism, endemic to southern Africa. The name comes from the ancient Greek ''adros'' (=thick) and ''mischos'' (= ...
''
Lem.
* ''
Cotyledon
A cotyledon ( ; ; "a cavity, small cup, any cup-shaped hollow",
gen. (), ) is a "seed leaf" – a significant part of the embryo within the seed of a plant – and is formally defined as "the embryonic leaf in seed-bearing plants, one or mor ...
''
L.
* ''
Kalanchoe
''Kalanchoe'' ( ), (also called "kalanchöe" or "kalanchoë"), is a genus of about 125 species of tropical, succulent plants in the stonecrop family Crassulaceae, mainly native to Madagascar and tropical Africa. A ''Kalanchoe'' species was one ...
''
Adans. (including ''
Bryophyllum
''Bryophyllum'' (from the Greek ''bryon/bryein'' = sprout, ''phyllon'' = leaf) is a group of plant species of the family (biology), family Crassulaceae native to Madagascar. It is a Section (botany), section or subgenus within the genus ''Kalan ...
''
Adans., ''Kitchingia''
Adans.)
* ''
Tylecodon
''Tylecodon'' is a genus of succulent plants in the family Crassulaceae, native to southern Africa.
Until the late 1970s all these plants were included in the genus ''Cotyledon'', but in 1978 Helmut Toelken of the Botanical Research Institute, ...
''
Toelken
= Sempervivoideae Arn.
George Arnott Walker Arnott of Arlary (6 February 1799 – 17 April 1868) was a Scottish botanist. He collaborated with botanists from around the world and served as a regius professor of botany at the University of Glasgow. An orchid genus ' ...
=
Sempervivoideae is the largest and taxonomically most complex subfamily, distributed in temperate climates, with about 20–30 genera, and divided into five
tribes
The term tribe is used in many different contexts to refer to a category of human social group. The predominant worldwide use of the term in English is in the discipline of anthropology. The definition is contested, in part due to conflict ...
, of which Sedeae contains two distinct clades, Leucosedum and Acre:
* Telephieae
* Umbiliceae
* Semperviveae
* Aeonieae
* Sedeae
Distribution and habitat
The family Crassulaceae has a cosmopolitan distribution, particularly ''Crassula'', though rare in South America and Australia, predominantly in the
temperate
In geography, the temperate climates of Earth occur in the middle latitudes (approximately 23.5° to 66.5° N/S of the Equator), which span between the tropics and the polar regions of Earth. These zones generally have wider temperature ran ...
and
subtropical
The subtropical zones or subtropics are geographical zone, geographical and Köppen climate classification, climate zones immediately to the Northern Hemisphere, north and Southern Hemisphere, south of the tropics. Geographically part of the Ge ...
regions of the Northern hemisphere and Africa. The main
centers of diversity being Mexico and south-western USA (about 300 species), Southern Africa (about 250 species), the
Mediterranean
The Mediterranean Sea ( ) is a sea connected to the Atlantic Ocean, surrounded by the Mediterranean basin and almost completely enclosed by land: on the east by the Levant in West Asia, on the north by Anatolia in West Asia and Southern ...
region (about 177 species) and adjacent
Macaronesia
Macaronesia (; ) is a collection of four volcanic archipelagos in the Atlantic Ocean#North Atlantic, North Atlantic Ocean, off the coast of North Africa and Europe. Each archipelago is made up of a number of list of islands in the Atlantic Oc ...
archipelago
An archipelago ( ), sometimes called an island group or island chain, is a chain, cluster, or collection of islands. An archipelago may be in an ocean, a sea, or a smaller body of water. Example archipelagos include the Aegean Islands (the o ...
(200 species), and south-eastern Asia (about 200 species), especially the Himalayas. The Mediterranean region includes 12 genera. The greatest diversity is in southern Africa and Madagascar where the Crassula and Kalanchoe clades are confined.
Habitat
Crassulaceae are found predominantly in
semi-arid
A semi-arid climate, semi-desert climate, or steppe climate is a aridity, dry climate sub-type. It is located on regions that receive precipitation below Evapotranspiration#Potential evapotranspiration, potential evapotranspiration, but not as l ...
rocky habitats with
monsoonal
A monsoon () is traditionally a seasonal reversing wind accompanied by corresponding changes in precipitation but is now used to describe seasonal changes in atmospheric circulation and precipitation associated with annual latitudinal oscill ...
patterns of precipitation and high humidity, while some genera (e.g. ''Sempervivum'') occur primarily in arid
mountainous
A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited summit area, and is usually higher t ...
habitats and higher altitudes. Although their succulent leaves and Crassulacean acid metabolism allow them to adapt to a variable water supply, they are not found in true
desert
A desert is a landscape where little precipitation occurs and, consequently, living conditions create unique biomes and ecosystems. The lack of vegetation exposes the unprotected surface of the ground to denudation. About one-third of the la ...
areas. Some lineages have adapted to semi-aquatic and seasonally
aquatic
Aquatic means relating to water; living in or near water or taking place in water; does not include groundwater, as "aquatic" implies an environment where plants and animals live.
Aquatic(s) may also refer to:
* Aquatic animal, either vertebrate ...
areas (''Crassula,'' ''Tillaea'', ''Sedella'') while Echeveria and Aichryson are found in moist, cool forest areas.
Ecology
While most Crassulaceae are perennial, ''Tillaea'' are annuals, and annual species are also found among ''Aichryson'', ''Crassula'', ''Sedum'' and ''Monanthes''.
Cultivation
Many Crassulaceae species are cultivated as pot plants or in rock gardens and borders.
Toxicity
Some species are toxic to animals, such as those of ''
Cotyledon
A cotyledon ( ; ; "a cavity, small cup, any cup-shaped hollow",
gen. (), ) is a "seed leaf" – a significant part of the embryo within the seed of a plant – and is formally defined as "the embryonic leaf in seed-bearing plants, one or mor ...
'' and ''
Tylecodon
''Tylecodon'' is a genus of succulent plants in the family Crassulaceae, native to southern Africa.
Until the late 1970s all these plants were included in the genus ''Cotyledon'', but in 1978 Helmut Toelken of the Botanical Research Institute, ...
'', e.g. ''Tylecodon wallichii''. All species of ''Kalanchoe'' are toxic, particularly to livestock in Australia and South Africa, where alternative forage is scarce, with the flowers containing the highest concentration of
cardiotoxins
Cardiotoxicity is the occurrence of heart dysfunction as electric or muscle damage, resulting in heart toxicity. This can cause heart failure, arrhythmia, myocarditis, and cardiomyopathy in patients. Some effects are reversible, while in others, p ...
, the active ingredient being
bufadienolide
Bufadienolide is a chemical compound with steroid structure. Its derivatives are collectively known as bufadienolides, including many in the form of bufadienolide glycosides (bufadienolides that contain structural groups derived from sugars). These ...
s (named for their
digoxin
Digoxin (better known as digitalis), sold under the brand name Lanoxin among others, is a medication used to treat various heart disease, heart conditions. Most frequently it is used for atrial fibrillation, atrial flutter, and heart failure. ...
-like effect on ''
Bufo
''Bufo'' is a genus of true toads in the amphibian family Bufonidae. As traditionally defined, it was a wastebasket genus containing a large number of toads from much of the world but following taxonomic reviews most of these have been moved to ...
'' toads). Illness in domestic pets has also been reported, ''
Kalanchoe blossfeldiana
''Kalanchoe blossfeldiana'' is a commonly cultivated evergreen house plant of the genus ''Kalanchoe'' native to Madagascar. It is known by the English common names flaming Katy, Christmas kalanchoe, florist kalanchoe and Madagascar widow's-thrill ...
'' being a popular Christmas time decorative household plant.
Uses

Although no species have a role as
crops
A crop is a plant that can be grown and harvested extensively for profit or subsistence. In other words, a crop is a plant or plant product that is grown for a specific purpose such as food, fibre, or fuel.
When plants of the same species a ...
, they are popular
horticultural
Horticulture (from ) is the art and science of growing fruits, vegetables, flowers, trees, shrubs and ornamental plants. Horticulture is commonly associated with the more professional and technical aspects of plant cultivation on a smaller and mo ...
commodities as
ornamental plants
Ornamental plants or ''garden plants'' are plants that are primarily grown for their beauty but also for qualities such as scent or how they shape physical space. Many flowering plants and garden varieties tend to be specially bred cultivars th ...
e.g. ''Kalanchoe'', while others (e.g. ''
Crassula helmsii
''Crassula helmsii'', known as swamp stonecrop or New Zealand pigmyweed, is an aquatic or semiterrestrial species of succulent plant in the family Crassulaceae. Originally found in Australia and New Zealand, it has been introduced around the wor ...
'') may also have a nuisance role as
weed
A weed is a plant considered undesirable in a particular situation, growing where it conflicts with human preferences, needs, or goals.Harlan, J. R., & deWet, J. M. (1965). Some thoughts about weeds. ''Economic botany'', ''19''(1), 16-24. Pla ...
s.
Notes
References
Bibliography
Books
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full text at'
ResearchGate
ResearchGate is a European commercial social networking site for scientists and researchers to share papers, ask and answer questions, and find collaborators. According to a 2014 study by ''Nature'' and a 2016 article in ''Times Higher Education' ...
)
*
Chapters
* , in
* , in
* , in
* , in
* , in
Historical
*
*
*
*
*
* , ''see also''
Species Plantarum
' (Latin for "The Species of Plants") is a book by Carl Linnaeus, originally published in 1753, which lists every species of plant known at the time, classified into genus, genera. It is the first work to consistently apply binomial nomenclature ...
*
Articles
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Phylogeny
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Websites
*
* (''see also''
Angiosperm Phylogeny Website
The Angiosperm Phylogeny Website (or APweb) is a website that presents up-to-date research on the phylogeny and taxonomy of flowering plants (angiosperms) in what is intended to be a user-friendly way.
The site is hosted by the Missouri Botanical ...
)
* , in
Flora of China online vol. 8
*
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Databases
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External links
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{{Authority control
Saxifragales families
Succulent plants