genus
Genus (; : genera ) is a taxonomic rank above species and below family (taxonomy), family as used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In bino ...
of
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 in the cabbage family,
Brassicaceae
Brassicaceae () or (the older but equally valid) Cruciferae () is a medium-sized and economically important Family (biology), family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous pla ...
. It includes more than 150
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), ...
, both popular garden plants and many wild forms. ''Erysimum'' is characterised by star-shaped and/or two-sided)
trichomes
Trichomes (; ) are fine outgrowths or appendages on plants, algae, lichens, and certain protists. They are of diverse structure and function. Examples are hairs, glandular hairs, scales, and papillae. A covering of any kind of hair on a plant ...
growing from the stem, with yellow, red, pink or orange flowers and multiseeded seed pods.
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 ...
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 ...
s or sub-shrubs. The perennial species are short-lived and in cultivation treated as biennials. Most species have stems erect, with a covering of bifid hairs, usually 25 ± 53cm × 2–3mm in size. The leaves are narrow and fixed. The lower leaves are broad and round with backwardly directed lobes, 50–80mm × 0.5–3mm. Stem leaves are linear, entire, growing whitish with 2-fid hairs; 21–43mm × 1.5–2mm. Flower clusters grow at intervals on short equal stalks along the stem, with bright yellow to red or pink bilateral
flower
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 ...
s. Flowering occurs during spring and summer. One species, '' Erysimum semperflorens'', native to Morocco and Algeria, has white flowers. The flowering part of the stem ranges from 4 to 7mm. There are four pouch-shaped
sepal
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'' ...
s, light green, 5–7mm × 1.5–2mm.
Etymology
The genus name ''Erysimum'' is derived from the Ancient Greek ''erysimon'' (, '' Sisymbrium officinale'' or , the hedgenettle), itself from the word ''eryo'' () meaning to drag or ''eryso'', a form of ''rhyomai'' (), meaning "to ward off" or "to heal" in reference to its medicinal properties.
The common name "wallflower" derives from the plant's ability to grow successfully in loose wall mortar.
Distribution
Wallflowers are native to temperate Eurasia, North Africa and
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 ...
, and North America south to Costa Rica. Many wallflowers are
endemic
Endemism is the state of a species being found only in a single defined geographic location, such as an island, state, nation, country or other defined zone; organisms that are indigenous to a place are not endemic to it if they are also foun ...
Mount Etna
Mount Etna, or simply Etna ( or ; , or ; ; or ), is an active stratovolcano on the east coast of Sicily, Italy, in the Metropolitan City of Catania, between the cities of Messina, Italy, Messina and Catania. It is located above the Conve ...
cultivar
A cultivar is a kind of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and which retains those traits when Plant propagation, propagated. Methods used to propagate cultivars include division, root a ...
s (e.g. ''Erysimum'' 'Chelsea Jacket') are derived from '' E. cheiri'' (often placed in ''Cheiranthus''), from southern Europe. They are often attacked by fungal and bacterial disease, so they are best grown as biennials and discarded after flowering. They are also susceptible to
clubroot
Clubroot is a common disease of cabbages, broccoli, cauliflower, Brussels sprouts, radishes, turnips, Matthiola, stocks, Erysimum, wallflowers and other plants of the family Brassicaceae (Cruciferae). It is caused by ''Plasmodiophora brassicae'' ...
, a disease of
Brassicaceae
Brassicaceae () or (the older but equally valid) Cruciferae () is a medium-sized and economically important Family (biology), family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous pla ...
. Growth is best in dry soils with very good drainage, and they are often grown successfully in loose wall mortar. There is a wide range of flower color in the warm spectrum, including white, yellow, orange, red, pink, maroon, purple and russet. The flowers, appearing in spring, usually have a strong, pleasant fragrance. Wallflowers are often associated in spring
bedding
Bedding, also called bedclothes or bed linen, is the materials laid above the mattress of a bed for hygiene, warmth, protection of the mattress, and decorative effect. Bedding is the removable and washable portion of a human sleeping environment ...
schemes with
tulip
Tulips are spring-blooming perennial herbaceous bulbiferous geophytes in the ''Tulipa'' genus. Their flowers are usually large, showy, and brightly coloured, generally red, orange, pink, yellow, or white. They often have a different colour ...
s and forget-me-nots.
The cultivar 'Bowles's Mauve' has gained the
Royal Horticultural Society
The Royal Horticultural Society (RHS), founded in 1804 as the Horticultural Society of London, is the UK's leading gardening charity.
The RHS promotes horticulture through its five gardens at Wisley (Surrey), Hyde Hall (Essex), Harlow Carr ...
's
Award of Garden Merit
The Award of Garden Merit (AGM) is a long-established award for plants by the British Royal Horticultural Society (RHS). It is based on assessment of the plants' performance under UK growing conditions.
It includes the full range of cultivated p ...
. It can become a bushy evergreen perennial in milder locations. It is strongly scented and attractive to bees.
Ecology
''Erysimum'' is found in a range of habitats across the northern hemisphere, and has developed diverse morphology and growth habits (herbaceous annual or perennial, and woody perennial). Different ''Erysimum'' species are used as food plants by the
larva
A larva (; : larvae ) is a distinct juvenile form many animals undergo before metamorphosis into their next life stage. Animals with indirect development such as insects, some arachnids, amphibians, or cnidarians typically have a larval phase ...
e of some
Lepidoptera
Lepidoptera ( ) or lepidopterans is an order (biology), order of winged insects which includes butterflies and moths. About 180,000 species of the Lepidoptera have been described, representing 10% of the total described species of living organ ...
(
butterflies
Butterflies are winged insects from the lepidopteran superfamily Papilionoidea, characterized by large, often brightly coloured wings that often fold together when at rest, and a conspicuous, fluttering flight. The oldest butterfly fossi ...
and
moth
Moths are a group of insects that includes all members of the order Lepidoptera that are not Butterfly, butterflies. They were previously classified as suborder Heterocera, but the group is Paraphyly, paraphyletic with respect to butterflies (s ...
s) species including the
garden carpet
The garden carpet (''Xanthorhoe fluctuata'') is a moth of the family Geometridae. It is an abundant and familiar species across its huge range which covers the whole Palearctic region from Ireland to Japan and including the Near East and North Af ...
(''Xanthorhoe fluctuata''). In addition, some species of weevils, like '' Ceutorhynchus chlorophanus'', live inside the fruits feeding on the developing seeds. Many species of beetles, bugs and grasshoppers eat the leaves and stalks. Some
mammal
A mammal () is a vertebrate animal of the Class (biology), class Mammalia (). Mammals are characterised by the presence of milk-producing mammary glands for feeding their young, a broad neocortex region of the brain, fur or hair, and three ...
ian herbivores, for example mule deer ('' Odocoileus hemionus'') in North America, argali ('' Ovis ammon'') in Mongolia, red deer (''
Cervus elaphus
The red deer (''Cervus elaphus'') is one of the largest deer species. A male red deer is called a stag or Hart (deer), hart, and a female is called a doe or hind. The red deer inhabits most of Europe, the Caucasus Mountains region, Anatolia, Ir ...
'') in Central Europe, or Spanish ibex ('' Capra pyrenaica'') in the Iberian Peninsula, feed on wallflower flowering and fruiting stalks. '' Erysimum crepidifolium'' (pale wallflower) is toxic to some generalist vertebrate herbivores.Bleicher Schöterich (''Erysimum crepidifolium''). In: giftpflanzen.com. /ref>
Most wallflowers are pollinator-generalists, their flowers being visited by many different species of bees, bee flies, hoverflies, butterflies, beetles, and ants. However, there are some specialist species. For example, '' Erysimum scoparium'' is pollinated almost exclusively by '' Anthophora alluadii''.
Defensive compounds
Like most
Brassicaceae
Brassicaceae () or (the older but equally valid) Cruciferae () is a medium-sized and economically important Family (biology), family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous pla ...
, species in the genus ''Erysimum'' produce
glucosinolates
Glucosinolates are natural components of many pungent plants such as mustard, cabbage, and horseradish. The pungency of those plants is due to mustard oils produced from glucosinolates when the plant material is chewed, cut, or otherwise dama ...
as defensive compounds. However, unlike almost all other genera in the Brassicaceae, ''Erysimum'' also accumulates cardiac glycosides, another class of
phytochemicals
Phytochemicals are naturally-occurring chemicals present in or extract, extracted from plants. Some phytochemicals are nutrients for the plant, while others are metabolites produced to enhance plant survivability and reproduction.
The field ...
with an ecological importance in insect defense. Cardiac glycosides specifically function to prevent insect
herbivory
A herbivore is an animal anatomically and physiologically evolved to feed on plants, especially upon vascular tissues such as foliage, fruits or seeds, as the main component of its diet. These more broadly also encompass animals that eat n ...
and/or
oviposition
The ovipositor is a tube-like organ used by some animals, especially insects, for the laying of eggs. In insects, an ovipositor consists of a maximum of three pairs of appendages. The details and morphology of the ovipositor vary, but typica ...
by blocking
ion channel
Ion channels are pore-forming membrane proteins that allow ions to pass through the channel pore. Their functions include establishing a resting membrane potential, shaping action potentials and other electrical signals by Gating (electrophysiol ...
function in muscle cells. These chemicals are toxic enough to deter generalist, and even some specialist insect herbivores.
Cardiac glycoside
Cardiac glycosides are a class of organic compounds that increase the output force of the heart and decrease its rate of contractions by inhibiting the cellular sodium-potassium ATPase pump. Their beneficial medical uses include treatments for ...
production is widespread in ''Erysimum'', with at least 48 species in the genus containing these compounds. Accumulation of cardiac glycosides in '' Erysimum crepidifolium'', but not other tested species, is induced by treatment with jasmonic acid and methyl jasmonate, endogenous elicitors of chemical defenses in many plant species. Molecular
phylogenetic
In biology, phylogenetics () is the study of the evolutionary history of life using observable characteristics of organisms (or genes), which is known as phylogenetic inference. It infers the relationship among organisms based on empirical dat ...
analysis indicates that ''Erysimum'' diversification from other
Brassicaceae
Brassicaceae () or (the older but equally valid) Cruciferae () is a medium-sized and economically important Family (biology), family of flowering plants commonly known as the mustards, the crucifers, or the cabbage family. Most are herbaceous pla ...
species that do not produce cardiac glycosides began in the
Pliocene
The Pliocene ( ; also Pleiocene) is the epoch (geology), epoch in the geologic time scale that extends from 5.33 to 2.58 suggesting relatively recent evolution of cardiac glycosides as a defensive trait in this genus.
Escape from herbivory
The evolution of novel chemical defenses in plants, such as
cardenolide
A cardenolide is a type of steroid. Many plants contain derivatives, collectively known as cardenolides, including many in the form of cardenolide glycosides (cardenolides that contain structural groups derived from sugars). Cardenolide glycoside ...
s in the genus ''Erysimum'', is predicted to allow escape from herbivory by specialist herbivores and expansion into new ecological niches. The crucifer-feeding specialist '' Pieries rapae'' (white cabbage butterfly) is deterred from feeding and oviposition by cardenolides in '' Erysimum cheiranthoides.'' Similarly, ''Anthocharis cardamines'' (orange tip butterfly), which oviposits on almost all crucifer species, avoids '' E. cheiranthoides.'' ''Erysimum asperum'' (western wallflower) is resistant to feeding and oviposition of ''Pieris napi macdunnoughii'' (synonym '' Pieris marginalis'', margined white butterfly). Two crucifer-feeding beetles, ''Phaedon'' sp. and '' Phyllotreta'' sp., were deterred from feeding by
cardenolide
A cardenolide is a type of steroid. Many plants contain derivatives, collectively known as cardenolides, including many in the form of cardenolide glycosides (cardenolides that contain structural groups derived from sugars). Cardenolide glycoside ...
s that were applied to their preferred food plants. Consistent with the hypothesis of enhanced speciation after escape from herbivory, phylogenetic studies involving 128 ''Erysimum'' species indicate diversification in Eurasia between 0.5 and 2 million years ago, and in North America between 0.7 and 1.65 million years ago.) This evolutionarily rapid expansion of the ''Erysimum'' genus has resulted in several hundred known species distributed throughout the northern hemisphere.
Ethnobotanical uses of ''Erysimum''
''Erysimum'' species have a long history of use in traditional medicine. In ''
Naturalis Historia
The ''Natural History'' () is a Latin work by Pliny the Elder. The largest single work to have survived from the Roman Empire to the modern day, the ''Natural History'' compiles information gleaned from other ancient authors. Despite the work' ...
'' by
Pliny the Elder
Gaius Plinius Secundus (AD 23/24 79), known in English as Pliny the Elder ( ), was a Roman Empire, Roman author, Natural history, naturalist, and naval and army commander of the early Roman Empire, and a friend of the Roman emperor, emperor Vesp ...
(), ''Erysimum'' is classified as a medicinal rather than a food plant. '' Erysimum cheiri'' is described as a medicinal herb in ''
De Materia Medica
(Latin name for the Greek work , , both meaning "On Medical Material") is a pharmacopoeia of medicinal plants and the medicines that can be obtained from them. The five-volume work was written between 50 and 70 CE by Pedanius Dioscorides, ...
'' by
Pedanius Dioscorides
Pedanius Dioscorides (, ; 40–90 AD), "the father of pharmacognosy", was a Greek physician, pharmacologist, botanist, and author of (in the original , , both meaning "On Medical Material") , a 5-volume Greek encyclopedic pharmacopeia on he ...
(), which was the predominant European medical
pharmacopeia
A pharmacopoeia, pharmacopeia, or pharmacopoea (or the typographically obsolete rendering, ''pharmacopœia''), meaning "drug-making", in its modern technical sense, is a reference work containing directions for the identification of compound med ...
for more than 1,500 years. Other
medieval
In the history of Europe, the Middle Ages or medieval period lasted approximately from the 5th to the late 15th centuries, similarly to the post-classical period of World history (field), global history. It began with the fall of the West ...
descriptions of medicinal herbs and their uses, including the ''Dispensatorium des Cordus'' by Valerius Cordus (1542), ''Bocks Kräuterbuch'' by Hieronymus Bock (1577), and Tabernaemontanus' ''Neuw Kreuterbuch'' by Jacobus Theodorus Tabernaemontanus (1588), also discuss applications of '' E. cheiri''. In traditional Chinese medicine, '' Erysimum cheiranthoides'' has been used to treat heart disease and other ailments. Although medical uses of ''Erysimum'' became uncommon in
Europe
Europe is a continent located entirely in the Northern Hemisphere and mostly in the Eastern Hemisphere. It is bordered by the Arctic Ocean to the north, the Atlantic Ocean to the west, the Mediterranean Sea to the south, and Asia to the east ...
after the
Middle Ages
In the history of Europe, the Middle Ages or medieval period lasted approximately from the 5th to the late 15th centuries, similarly to the post-classical period of global history. It began with the fall of the Western Roman Empire and ...
, ''Erysimum diffusum,'' as well as purified erysimin and erysimoside, have been applied more recently as Ukrainian ethnobotanical treatments.
Erysimum capitatum
''Erysimum capitatum'' is a species of Erysimum, wallflower known commonly as the sanddune wallflower, western wallflower, or prairie rocket.
This species can be found in regions across North America, from the Great Lakes to the West Coast of th ...