Clover | |
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Trifolium repens (white clover) | |
Scientific classification | |
Kingdom: | Plantae |
Clade: | Tracheophytes |
Clade: | Angiosperms |
Clade: | Eudicots |
Clade: | Rosids |
Order: | Fabales |
Family: | Fabaceae |
Subfamily: | Faboideae |
Clade: | Inverted repeat-lacking clade |
Tribe: | Trifolieae |
Genus: | Trifolium L. |
Subgenera and sections [1] | |
subg. Chronosemium
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Synonyms [2] | |
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Clover, also called trefoil, are plants of the genus Trifolium (from Latin tres 'three' + folium 'leaf'), consisting of about 300 species of flowering plants in the legume family Fabaceae originating in Europe. The genus has a cosmopolitan distribution with the highest diversity in the temperate Northern Hemisphere, but many species also occur in South America and Africa, including at high altitudes on mountains in the tropics. They are small annual, biennial, or short-lived perennial herbaceous plants, typically growing up to 30 centimetres (12 in) tall. The leaves are trifoliate (rarely, they have four or more leaflets; the more leaflets the leaf has, the rarer it is; see four-leaf clover), with stipules adnate to the leaf-stalk, and heads or dense spikes of small red, purple, white, or yellow flowers; the small, few-seeded pods are enclosed in the calyx. [3] Other closely related genera often called clovers include Melilotus (sweet clover) and Medicago (alfalfa or Calvary clover).
Several species of clover are extensively cultivated as fodder plants. The most widely cultivated clovers are white clover, Trifolium repens, and red clover, Trifolium pratense. Clover, either sown alone or in mixture with ryegrass, has for a long time formed a staple crop for silaging, for several reasons: it grows freely, shooting up again after repeated mowings; it produces an abundant crop; it is palatable to and nutritious for livestock; it fixes nitrogen, reducing the need for synthetic fertilizers; it grows in a great range of soils and climates; and it is appropriate for either pasturage or green composting. [3]
In many areas, particularly on acidic soil, clover is short-lived because of a combination of insect pests, diseases and nutrient balance; this is known as "clover sickness". When crop rotations are managed so that clover does not recur at intervals shorter than eight years, it grows with much of its pristine vigor. [3]
Clovers are most efficiently pollinated by bumblebees, which have declined as a result of agricultural intensification. [4] Honeybees can also pollinate clover, and beekeepers are often in heavy demand from farmers with clover pastures. Farmers reap the benefits of increased reseeding that occurs with increased bee activity, which means that future clover yields remain abundant. Beekeepers benefit from the clover bloom, as clover is one of the main nectar sources for honeybees. [5]
Trifolium repens , white or Dutch clover, is a perennial abundant in meadows and good pastures. The flowers are white or pinkish, becoming brown and deflexed as the corolla fades. Trifolium hybridum , alsike or Swedish clover, is a perennial which was introduced early in the 19th century and has now become naturalized in Britain. The flowers are white or rosy, and resemble those of Trifolium repens. Trifolium medium , meadow or zigzag clover, a perennial with straggling flexuous stems and rose-purple flowers, [3] has potential for interbreeding with T. pratense to produce perennial crop plants. [6]
Other species are: Trifolium arvense , hare's-foot trefoil; found in fields and dry pastures, a soft hairy plant with minute white or pale pink flowers and feathery sepals; Trifolium fragiferum , strawberry clover, with globose, rose-purple heads and swollen calyxes; Trifolium campestre , hop trefoil, on dry pastures and roadsides, the heads of pale yellow flowers suggesting miniature hops; and the somewhat similar Trifolium dubium , common in pastures and roadsides, with smaller heads and small yellow flowers turning dark brown. [3]
Clover is foraged for by wildlife such as bears, game animals, and birds. Clover is edible by humans, [7] although red clover should be avoided by pregnant women. [8] The plant is a traditional Native American food, [9] which is eaten both raw and after drying and smoking the roots. The seeds from the blossoms are used to make bread. [10] It is also possible to make tea from the blossoms. [10]
Shamrock, the traditional Irish symbol, which according to legend was coined by Saint Patrick for the Holy Trinity, is commonly associated with clover, although alternatively sometimes with the various species within the genus Oxalis , which are also trifoliate. [11]
Clovers occasionally have four leaflets, instead of the usual three. These four-leaf clovers, like other rarities, are considered lucky. [3] Clovers can also have five, six, or more leaflets, but these are rarer still. The clover's outer leaf structure varies in physical orientation.
The record for most leaflets is 63, set on August 2, 2023, by Yoshiharu Watanabe in Japan. [12] The previous record holder, Shigeo Obara, had discovered an 18-leaf clover in 2002, [13] a 21-leaf clover in 2008 [14] and a 56-leaf clover in 2009, [15] also in Japan.
The first extensive classification of Trifolium had been done by Michael Zohary and David Heller, and it was subsequently released in 1984. They divided the genus into eight sections: Lotoidea, Paramesus, Mistyllus, Vesicamridula, Chronosemium, Trifolium, Trichoecephalum, and Involucrarium, with Lotoidea placed most basally. [18] Within this classification system, Trifolium repens falls within section Lotoidea, the largest and least heterogeneous section. Lotoidea contains species from America, Africa, and Eurasia, considered a clade because of their inflorescence shape, floral structure, and legume that protrudes from the calyx. However, these traits are not unique to the section, and are shared with many other species in other sections. Zohary and Heller argued that the presence of these traits in other sections proved the basal position of Lotoidea, because they were ancestral. Aside from considering this section basal, they did not propose relationships between other sections. Since then, molecular data has both questioned and confirmed the proposed phylogeny from Zohary and Heller. A genus-wide molecular study has since proposed a new classification system, made up of two subgenera, Chronosemium and Trifolium. [19] This recent reclassification further divides subgenus Trifolium into eight sections. The molecular data supports the monophyletic nature of three sections proposed by Zohary and Heller (Tripholium, Paramesus, and Trichoecepalum), but not of Lotoidea (members of this section have since been reclassified into five other sections). Other molecular studies, although smaller, support the need to reorganize Lotoidea. [20] [21]
291 species of Trifolium are accepted: [2]
Lathyrus is a genus of flowering plants in the legume family Fabaceae, and contains approximately 160 species. Commonly known as peavines or vetchlings, they are native to temperate areas, with a breakdown of 52 species in Europe, 30 species in North America, 78 in Asia, 24 in tropical East Africa, and 24 in temperate South America. There are annual and perennial species which may be climbing or bushy. This genus has numerous sections, including Orobus, which was once a separate genus. The genus has numerous synonyms, including Pisum, the ancient Latin name for the pea.
Trifolium repens, the white clover, is a herbaceous perennial plant in the bean family Fabaceae. It is native to Europe, including the British Isles, and central Asia and is one of the most widely cultivated types of clover. It has been widely introduced worldwide as a forage crop, and is now also common in most grassy areas of North America, Australia and New Zealand. The species includes varieties often classed as small, intermediate and large, according to height, which reflects petiole length. The term 'white clover' is applied to the species in general, 'Dutch clover' is often applied to intermediate varieties, and 'ladino clover' is applied to large varieties.
Cardamine is a large genus of flowering plants in the mustard family, Brassicaceae, known as bittercresses and toothworts. It contains more than 200 species of annuals and perennials. Species in this genus can be found in diverse habitats worldwide, except the Antarctic. The name Cardamine is derived from the Greek kardaminē, water cress, from kardamon, pepper grass.
Carduus is a genus of flowering plants in the family Asteraceae, and the tribe Cardueae, one of two genera considered to be true thistles, the other being Cirsium. Plants of the genus are known commonly as plumeless thistles. They are native to temperate Eurasia and North Africa, and several are known elsewhere as introduced species. This genus is noted for its disproportionately high number of noxious weeds compared to other flowering plant genera.
Epilobium is a genus of flowering plants in the family Onagraceae, containing about 197 species. The genus has a worldwide distribution. It is most prevalent in the subarctic, temperate and subantarctic regions, whereas in the subtropics and tropics Epilobium species are restricted to the cool montane biomes, such as the New Guinea Highlands.
Minuartia is a genus of flowering plants commonly known as sandworts in the family Caryophyllaceae.
Draba is a large genus of flowering plants in the family Brassicaceae, commonly known as whitlow-grasses.
Erodium is a genus of flowering plants in the botanical family Geraniaceae. The genus includes about 120 species with a subcosmopolitan distribution, native to Europe, North Africa, Asia, Australia, and more locally in North and South America. They are perennials, annuals, or subshrubs, with five-petalled flowers in shades of white, pink, and purple, that strongly resemble the better-known Geranium (crane's-bills). In English-speaking areas of Europe, the species are known as stork's-bills. In North America they are known as filarees or heron's bill.
Dalea is a genus of flowering plants in the legume family, Fabaceae. Members of the genus are commonly known as prairie clover or indigo bush. Its name honors English apothecary Samuel Dale (1659–1739). They are native to the Western hemisphere, where they are distributed from Canada to Argentina. Nearly half of the known species are endemic to Mexico. Two species of Dalea have been considered for rangeland restoration.
Valerianella is a genus of flowering plant in family Caprifoliaceae. It includes 23 species native to the Mediterranean Basin of southern Europe and North Africa, western and central Asia, Madeira and the Azores, and Ethiopia and Kenya. Many species formerly placed in Valerianella, including those native to the Americas, have been moved to Valeriana. Plants of Valerianella and Valeriana are sometimes known by the common name corn salad or cornsalad.
Eremogone is a genus of flowering plants in the family Caryophyllaceae, native to western North America, northern Asia, eastern Europe and northeastern Africa. Attempts to resolve taxonomic relationships within the Caryophyllaceae have resulted in the enlargement of Eremogone with species from other genera.