The Ericaceae () are a

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 ...

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, commonly known as the heath or heather family, found most commonly in acidic and infertile growing conditions. The family is large, with about 4,250 known species spread across 124 genera, making it the 14th most species-rich family of flowering plants. The many well known and economically important members of the Ericaceae include the

cranberry Cranberries are a group of evergreen dwarf shrubs or trailing vines in the subgenus ''Oxycoccus'' of the genus ''Vaccinium''. Cranberries are low, creeping shrubs or vines up to long and in height; they have slender stems that are not th ...

blueberry Blueberries are a widely distributed and widespread group of perennial flowering plants with blue or purple berries. They are classified in the section ''Cyanococcus'' with the genus ''Vaccinium''. Commercial blueberries—both wild (lowbush) ...

huckleberry Huckleberry is a name used in North America for several plants in the family Ericaceae, in two closely related genera: ''Vaccinium'' and ''Gaylussacia''. Nomenclature The name 'huckleberry' is a North American variation of the English dialectal ...

rhododendron ''Rhododendron'' (; : ''rhododendra'') is a very large genus of about 1,024 species of woody plants in the Ericaceae, heath family (Ericaceae). They can be either evergreen or deciduous. Most species are native to eastern Asia and the Himalayan ...

(including

azalea Azaleas ( ) are flowering shrubs in the genus ''Rhododendron'', particularly the former sections ''Rhododendron sect. Tsutsusi, Tsutsusi'' (evergreen) and ''Pentanthera'' (deciduous). Azaleas bloom in the spring (April and May in the temperate ...

s), and various common heaths and heathers (''

Erica Erica or ERICA may refer to: * Erica (given name) * Erica (plant), ''Erica'' (plant), a flowering plant genus * Erica (chatbot), a service of Bank of America * Erica (video game), ''Erica'' (video game), a 2019 FMV video game * Erica (spider), ' ...

'', ''

Cassiope ''Cassiope'' is a genus of 18 small shrubby species in the family Ericaceae. It is the sole genus in the subfamily Cassiopoideae. They are native to the Arctic and north temperate montane regions. The genus is named after Cassiopeia of Greek ...

'', ''

Daboecia ''Daboecia'' , or St. Dabeoc's heath, is a small genus of flowering plants in the family (biology), family Ericaceae, containing two evergreen shrubs, closely related to the genus ''Erica (plant), Erica''. They are native plant, native to cliffs ...

'', and ''

Calluna ''Calluna vulgaris'', common heather, ling, or simply heather, is the sole species in the genus ''Calluna'' in the flowering plant family Ericaceae. It is a low-growing evergreen shrub growing to tall, or rarely to and taller, and is found wide ...

'' for example).

Description

The Ericaceae contain a morphologically diverse range of taxa, including

herb Herbs are a widely distributed and widespread group of plants, excluding vegetables, with savory or aromatic properties that are used for flavoring and garnishing food, for medicinal purposes, or for fragrances. Culinary use typically distingu ...

s, dwarf shrubs,

shrub A shrub or bush is a small to medium-sized perennial woody plant. Unlike herbaceous plants, shrubs have persistent woody stems above the ground. Shrubs can be either deciduous or evergreen. They are distinguished from trees by their multiple ...

s, and

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. Their leaves are usually

evergreen In botany, an evergreen is a plant which has Leaf, foliage that remains green and functional throughout the year. This contrasts with deciduous plants, which lose their foliage completely during the winter or dry season. Consisting of many diffe ...

, alternate or whorled, simple and without

stipule 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 (botany), petiole). They are primarily found among dicots and rare among monocots. Stipules are considered part ...

s. Their flowers are

hermaphrodite A hermaphrodite () is a sexually reproducing organism that produces both male and female gametes. Animal species in which individuals are either male or female are gonochoric, which is the opposite of hermaphroditic. The individuals of many ...

and show considerable variability. The

petal 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 ''corol ...

s are often fused (

sympetalous Sympetally (fused petals) is a flower characteristic that historically was used to classify a grouping of plants termed Sympetalae, but this term has been abandoned in newer molecular based classifications, although the grouping has similarity to ...

) with shapes ranging from narrowly tubular to funnelform or widely urn-shaped. The corollas are usually

radially symmetrical Symmetry in biology refers to the symmetry observed in organisms, including plants, animals, fungi, and bacteria. External symmetry can be easily seen by just looking at an organism. For example, the face of a human being has a plane of symme ...

(

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 ...

) and urn-shaped, but many flowers of the genus ''Rhododendron'' are somewhat

bilaterally symmetrical Symmetry in biology refers to the symmetry observed in organisms, including plants, animals, fungi, and bacteria. External symmetry can be easily seen by just looking at an organism. For example, the face of a human being has a plane of symme ...

(

zygomorphic 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 spir ...

). Anthers open by pores.

Taxonomy

Michel Adanson Michel Adanson (7 April 17273 August 1806) was an 18th-century French botanist and naturalist who traveled to Senegal to study flora and fauna. He proposed a "natural system" of taxonomy distinct from the binomial system forwarded by Linnaeus. ...

used the term Vaccinia to describe a similar family, but first used the term Ericaceae. The name comes from the type genus ''

'', which appears to be derived from the Greek word (). The exact meaning is difficult to interpret, but some sources show it as meaning 'heather'. The name may have been used informally to refer to the plants before Linnaean times, and simply been formalised when Linnaeus described ''Erica'' in 1753, and then again when Jussieu described the Ericaceae in 1789. Historically, the Ericaceae included both subfamilies and tribes. In 1971, Stevens, who outlined the history from 1876 and in some instances 1839, recognised six subfamilies (Rhododendroideae,

Ericoideae Ericoideae is a subfamily of Ericaceae, containing nineteen genera, and 1,790 species, the largest of which is ''Rhododendron'', followed by Erica. The Ericoideae bear spiral leaves with flat laminae. The pedicel is articulated and the flowers a ...

Vaccinioideae Vaccinioideae is a flowering plant, flowering-plant subfamily in the family Ericaceae. It contains the commercially important cranberry, blueberry, bilberry, lingonberry, and huckleberry. Taxonomy * Tribe: Andromedeae ** Genera: ''Andromeda polifo ...

Pyroloideae Pyroloideae is a family (biology), subfamily of plants in the family Ericaceae. It was formerly treated as a separate family, Pyrolaceae.Stevens, P.F. (2001 onwards).Ericaceae ''Angiosperm Phylogeny Website''. Retrieved 2014-12-29. It has also bee ...

Monotropoideae Monotropoideae, sometimes referred to as monotropes, are a flowering plant subfamily in the Family (biology), family Ericaceae. Members of this subfamily are notable for their mycoheterotrophic and non-photosynthesizing or achlorophyllous characte ...

, and Wittsteinioideae), and further subdivided four of the subfamilies into tribes, the Rhododendroideae having seven tribes (Bejarieae, Rhodoreae, Cladothamneae, Epigaeae, Phyllodoceae, and Diplarcheae). Within tribe Rhodoreae, five genera were described, ''

Rhododendron ''Rhododendron'' (; : ''rhododendra'') is a very large genus of about 1,024 species of woody plants in the Ericaceae, heath family (Ericaceae). They can be either evergreen or deciduous. Most species are native to eastern Asia and the Himalayan ...

'' L. (including ''Azalea'' L. pro parte), ''Therorhodion'' Small, '' Ledum'' L., ''Tsusiophyllum'' Max., ''

Menziesia ''Rhododendron'' sect. ''Sciadorhodion'' is a subsection of Rhododendron subg. Azaleastrum, subgenus ''Azaleastrum'' in the genus ''Rhododendron''. It comprises 16 species of deciduous shrubss native to East Asia and North America. Taxonomy Plan ...

'' J. E. Smith, that were eventually transferred into ''Rhododendron'', along with Diplarche from the monogeneric tribe Diplarcheae. In 2002, systematic research resulted in the inclusion of the formerly recognised families Empetraceae, Epacridaceae, Monotropaceae, Prionotaceae, and Pyrolaceae into the Ericaceae based on a combination of molecular, morphological, anatomical, and embryological data, analysed within a

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 ...

framework. The move significantly increased the morphological and geographical range found within the group. One possible classification of the resulting family includes 9 subfamilies, 126 genera, and about 4,000 species: *

Enkianthoideae ''Enkianthus'' is a genus of shrubs or small trees in the heath family (Ericaceae). Its native range is in Asia, as far west as the eastern Himalayas, as far south as Indochina, and as far north and east as China and Japan. This genus is consi ...

Kron, Judd & Anderberg (one genus, 16 species) *

Kosteltsky (4 genera, 40 species) *

Arnott (10 genera, 15 species) *

Arbutoideae The Arbutoideae are a subfamily in the plant family Ericaceae. Phylogenetic analysis supported all genera of the subfamily as monophyletic, except ''Arbutus''. Moreover, it was suggested that the non-sister relationship between Mediterranean and N ...

Niedenzu (up to six genera, about 80 species) *

Cassiopoideae ''Cassiope'' is a genus of 18 small shrubby species in the family Ericaceae. It is the sole genus in the subfamily Cassiopoideae. They are native to the Arctic and north temperate montane regions. The genus is named after Cassiopeia of Greek myt ...

Kron & Judd (one genus, 12 species) *

Link (19 genera, 1790 species) *

Harrimanelloideae ''Harrimanella'' is a genus of flowering plant in the heath family Ericaceae, with a single species, ''Harrimanella hypnoides'', also known as moss bell heather or moss heather. ''H. hypnoides'' is a cold hardy dicot perennial that produces mos ...

Kron & Judd (one species) *

Epacridoideae Epacridoideae is a subfamily of the family Ericaceae. The name Styphelioideae Sweet is also used. The subfamily contains around 35 genera and 545 species. Many species are found in Australasia, others occurring northwards through the Pacific to S ...

Arn. (=Styphelioideae Sweet) (35 genera, 545 species) *

Arnott (50 genera, 1580 species)

Genera

Distribution and ecology

The Ericaceae have a nearly worldwide distribution. They are absent from continental

Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarctic Circle and surrounded by the Southern Ocean (also known as the Antarctic Ocean), it contains the geographic South Pole. ...

, parts of the high

Arctic The Arctic (; . ) is the polar regions of Earth, polar region of Earth that surrounds the North Pole, lying within the Arctic Circle. The Arctic region, from the IERS Reference Meridian travelling east, consists of parts of northern Norway ( ...

, central

Greenland Greenland is an autonomous territory in the Danish Realm, Kingdom of Denmark. It is by far the largest geographically of three constituent parts of the kingdom; the other two are metropolitan Denmark and the Faroe Islands. Citizens of Greenlan ...

, northern and central

Australia Australia, officially the Commonwealth of Australia, is a country comprising mainland Australia, the mainland of the Australia (continent), Australian continent, the island of Tasmania and list of islands of Australia, numerous smaller isl ...

, and much of the lowland

tropics The tropics are the regions of Earth surrounding the equator, where the sun may shine directly overhead. This contrasts with the temperate or polar regions of Earth, where the Sun can never be directly overhead. This is because of Earth's ax ...

and

neotropics The Neotropical realm is one of the eight biogeographic realms constituting Earth's land surface. Physically, it includes the tropical terrestrial ecoregions of the Americas and the entire South American temperate zone. Definition In biogeog ...

. The family is largely composed of plants that can tolerate acidic, infertile, shady conditions. Due to their tolerance of acidic conditions, this plant family is also typical of peat

bog A bog or bogland is a wetland that accumulates peat as a deposit of dead plant materials often mosses, typically sphagnum moss. It is one of the four main types of wetlands. Other names for bogs include mire, mosses, quagmire, and musk ...

s and blanket bogs; examples include ''

Rhododendron groenlandicum ''Rhododendron groenlandicum'' (bog Labrador tea, muskeg tea, swamp tea, or in northern Canada, Hudson's Bay tea; formerly ''Ledum groenlandicum'' or ''Ledum latifolium'') is a flowering shrub with white flowers and evergreen leaves that is used ...

'' and species in the genus ''

Kalmia ''Kalmia'' is a genus of about ten species of evergreen shrubs from 0.2–5 m tall, in the family Ericaceae (heath). They are native to North America (mainly in the eastern half of the continent) and Cuba. They grow in acidic soils, with differe ...

''. In eastern

North America North America is a continent in the Northern Hemisphere, Northern and Western Hemisphere, Western hemispheres. North America is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South Ameri ...

, members of this family often grow in association with an

oak An oak is a hardwood tree or shrub in the genus ''Quercus'' of the beech family. They have spirally arranged leaves, often with lobed edges, and a nut called an acorn, borne within a cup. The genus is widely distributed in the Northern Hemisp ...

canopy, in a habitat known as an oak-heath forest. Plants in Ericaceae, especially species in ''

Vaccinium ''Vaccinium'' is a common and widespread genus of shrubs or dwarf shrubs in the heath family (Ericaceae). The fruits of many species are eaten by humans and some are of commercial importance, including the cranberry, blueberry, bilberry (wh ...

'', rely on

buzz pollination Buzz pollination or sonication is a technique used by some bees, such as solitary bees and bumblebees, to release pollen which is more or less firmly held by the anthers. The anthers of buzz-pollinated plant species are typically tubular, with an ...

for successful pollination to occur. The majority of ornamental species from ''Rhododendron'' are native to

East Asia East Asia is a geocultural region of Asia. It includes China, Japan, Mongolia, North Korea, South Korea, and Taiwan, plus two special administrative regions of China, Hong Kong and Macau. The economies of Economy of China, China, Economy of Ja ...

, but most varieties cultivated today are hybrids. Most rhododendrons grown in the United States are cultivated in the

Pacific Northwest The Pacific Northwest (PNW; ) is a geographic region in Western North America bounded by its coastal waters of the Pacific Ocean to the west and, loosely, by the Rocky Mountains to the east. Though no official boundary exists, the most common ...

. The United States is the top producer of both blueberries and cranberries, with the state of Maine growing the majority of

lowbush blueberry Blueberries are a widely distributed and widespread group of perennial flowering plants with blue or purple berries. They are classified in the section ''Cyanococcus'' with the genus ''Vaccinium''. Commercial blueberries—both wild (lowbush) ...

. The wide distribution of genera within Ericaceae has led to situations in which distinct American and European plants share the same common name, e.g. blueberry (''

Vaccinium corymbosum ''Vaccinium corymbosum'', the northern highbush blueberry, is a North American species of blueberry. Other common names include blue huckleberry, tall huckleberry, swamp huckleberry, high blueberry, and swamp blueberry. Description ''Vaccinium ...

'' in North America and ''V.'' ''myrtillus'' in Europe) and cranberry ( ''V.'' ''macrocarpon'' in America and ''V.'' ''oxycoccos'' in Europe).

Mycorrhizal relationships

Like other stress-tolerant plants, many Ericaceae have

mycorrhiza A mycorrhiza (; , mycorrhiza, or mycorrhizas) is a symbiotic association between a fungus and a plant. The term mycorrhiza refers to the role of the fungus in the plant's rhizosphere, the plant root system and its surroundings. Mycorrhizae play ...

l fungi to assist with extracting nutrients from infertile

soil Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...

s, as well as evergreen foliage to conserve absorbed nutrients. This trait is not found in the

Clethraceae The Clethraceae are a small family of flowering plants in the order Ericales, composed of two genera, '' Clethra'' and '' Purdiaea'', with approximately 75 species. They are native to warm temperate to tropical regions of Asia and the Americas, w ...

and

Cyrillaceae The Cyrillaceae are a small family of flowering plants in the order Ericales, native to warm temperate to tropical regions of the Americas. The family comprises two genera, '' Cliftonia'' and '' Cyrilla'', each containing a single species, ''Clif ...

, the two families most closely related to the Ericaceae. Most Ericaceae (excluding the Monotropoideae, and some Epacridoideae) form a distinctive accumulation of

mycorrhizae A mycorrhiza (; , mycorrhiza, or mycorrhizas) is a symbiotic association between a fungus and a plant. The term mycorrhiza refers to the role of the fungus in the plant's rhizosphere, the plant root system and its surroundings. Mycorrhizae play ...

, in which fungi grow in and around the roots and provide the plant with nutrients. The

are

mixotrophic A mixotroph is an organism that uses a mix of different sources of energy and carbon, instead of having a single trophic mode, on the continuum from complete autotrophy to complete heterotrophy. It is estimated that mixotrophs comprise more than ...

and gain sugars from the mycorrhizae, as well as nutrients. The cultivation of blueberries, cranberries, and

wintergreen Wintergreen is a group of aromatic plants. The term ''wintergreen'' once commonly referred to plants that remain green (continue photosynthesis) throughout the winter. The term ''evergreen'' is now more commonly used for this characteristic. ...

for their fruit and oils relies especially on these unique relationships with fungi, as a healthy mycorrhizal network in the soil helps the plants to resist environmental stresses that might otherwise damage crop yield. Ericoid mycorrhizae are responsible for a high rate of uptake of nitrogen, which causes naturally low levels of free nitrogen in ericoid soils. These mycorrhizal fungi may also increase the tolerance of Ericaceae to

heavy metals upright=1.2, Crystals of lead.html" ;"title="osmium, a heavy metal nearly twice as dense as lead">osmium, a heavy metal nearly twice as dense as lead Heavy metals is a controversial and ambiguous term for metallic elements with relatively h ...

in soil, and may cause plants to grow faster by producing

phytohormone Plant hormones (or phytohormones) are signal molecules, produced within plants, that occur in extremely low concentrations. Plant hormones control all aspects of plant growth and development, including embryogenesis, the regulation of organ si ...

Heathlands

In many parts of the world, a "heath" or "heathland" is an environment characterised by an open dwarf-

community found on low-quality acidic soils, generally dominated by plants in Ericaceae. Heathlands are a broadly anthropogenic habitat, requiring regular grazing or burning to prevent succession. Heaths are particularly abundantand constitute important cultural elementsin Norway, the United Kingdom, the Netherlands, Germany, Spain, Portugal, and other countries in Central and Western Europe. The most common examples of plants in Ericaceae which dominate heathlands are ''

Calluna vulgaris ''Calluna vulgaris'', common heather, ling, or simply heather, is the sole species in the genus ''Calluna'' in the flowering plant family Ericaceae. It is a low-growing evergreen shrub growing to tall, or rarely to and taller, and is found wide ...

'', '' Erica cineria'', ''

Erica tetralix ''Erica tetralix'', the cross-leaved heath, is a species of flowering plant in the family Ericaceae, native to western Europe. Description It is a perennial subshrub with glandular leaves in whorls of four (whence the name). Appearing in summe ...

'', and ''

Vaccinium myrtillus ''Vaccinium myrtillus'' or European blueberry is a Holarctic realm, holarctic species of shrub with edible fruit of blue color, known by the common names bilberry, blaeberry, wimberry, and whortleberry. It is more precisely called common bilberr ...

.'' In heathland, plants in Ericaceae serve as host plants to the butterfly ''

Plebejus argus The silver-studded blue (''Plebejus argus'') is a butterfly in the family Lycaenidae. It has bright blue wings rimmed in black with white edges and silver spots on its hindwings, lending it the name of the silver-studded blue. ''P. argus'' can be ...

''. Other insects, such as ''

Saturnia pavonia ''Saturnia pavonia'', the small emperor moth, is a moth of the family Saturniidae. It was first described by Carl Linnaeus in his 1758 10th edition of Systema Naturae, 10th edition of ''Systema Naturae''. Sometimes, the junior homonym, incorrec ...

'', '' Myrmeleotettix maculatus'', '' Metrioptera brachyptera'', and '' Picromerus bidens'' are closely associated with heathland environments. Reptiles thrive in heaths due to an abundance of sunlight and prey, and birds hunt the insects and reptiles which are present. Some evidence suggests

eutrophic Eutrophication is a general term describing a process in which nutrients accumulate in a body of water, resulting in an increased growth of organisms that may deplete the oxygen in the water; ie. the process of too many plants growing on the s ...

rainwater can convert ericoid heaths with species such as ''Erica tetralix'' to

grassland A grassland is an area where the vegetation is dominance (ecology), dominated by grasses (Poaceae). However, sedge (Cyperaceae) and rush (Juncaceae) can also be found along with variable proportions of legumes such as clover, and other Herbaceo ...

Nitrogen Nitrogen is a chemical element; it has Symbol (chemistry), symbol N and atomic number 7. Nitrogen is a Nonmetal (chemistry), nonmetal and the lightest member of pnictogen, group 15 of the periodic table, often called the Pnictogen, pnictogens. ...

is particularly suspect in this regard, and may be causing measurable changes to the distribution and abundance of some ericaceous species.

References

Bibliography

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