Clover - WikiHQ

Clovers, also called trefoils, are plants of the genus Trifolium (). They are herbaceous plants growing up to tall. The leaves are usually trifoliate and the small flowers are reddish to white or yellow. Related genera with similar common names include Melilotus (sweet clover) and Medicago (burclover).

The genus consists of about 300 species in the legume family, Fabaceae. Originating in Europe, the genus has a cosmopolitan distribution. A number of wild and domestic animals consume the plants. Clovers have been cultivated by humans for over 1,000 years, valued for their nitrogen fixation, which fertilizes the soil and bolsters the productivity of rotated crops.

Some forms of the plant are culturally significant, including the shamrock, used to represent Ireland, and the four-leaf clover, associated with good luck. Specimens with other numbers of leaflets have been found, the record high of 63 being recorded in 2023.

Description

They are small annual, biennial, or short-lived perennial herbaceous plants, typically growing up to tall. The leaves are trifoliate, but seldomly have more or less than three leaflets, being more rare the higher or lower the number. The stipules are adnate to the leaf-stalk. Small red, purple, white, or yellow flowers appear in heads or dense spikes. The small, few-seeded pods are enclosed in the calyx. 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. 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.

Species

291 species of Trifolium are accepted:

Trifolium productum
Trifolium prophetarum M. Hossain
Trifolium pseudomedium
Trifolium pseudostriatum Baker f.
Trifolium pulchellum
Trifolium purpureum Loisel.
Trifolium purseglovei J. B. Gillett
Trifolium quartinianum A. Rich.
Trifolium radicosum Boiss. & Hohen.
Trifolium rechingeri
Trifolium reflexum L. – buffalo clover
Trifolium repens L. – shamrock (white clover)
Trifolium resupinatum L. – Persian clover, shaftal
Trifolium retusum L.
Trifolium × retyezaticum
Trifolium rhizomatosum
Trifolium rhombeum
Trifolium riograndense Burkart
Trifolium rollinsii
Trifolium roussaeanum Boiss.
Trifolium rubens L.
Trifolium rueppellianum Fresen.
Trifolium salmoneum Mouterde
Trifolium sannineum
Trifolium sarosiense
Trifolium saxatile All.
Trifolium scabrum L.
Trifolium schimperi (Hochst.) A.Rich.
Trifolium schneideri
Trifolium × schwarzii
Trifolium scutatum Boiss.
Trifolium sebastiani Savi
Trifolium semipilosum Fresen.
Trifolium setiferum Boiss.
Trifolium simense Fresen.
Trifolium sintenisii Freyn
Trifolium siskiyouense J.M.Gillett
Trifolium somalense Taub. ex Harms
Trifolium sonorense
Trifolium spadiceum L.
Trifolium spananthum Thulin
Trifolium spumosum L.
Trifolium squamosum (or maritimum) L. – sea clover
Trifolium squarrosum L.
Trifolium stellatum L.
Trifolium steudneri Schweinf.
Trifolium stipulaceum Thunb.
Trifolium stoloniferum Muhl. ex A. Eaton – running buffalo clover
Trifolium stolzii Harms
Trifolium striatum L. – knotted clover
Trifolium strictum L.
Trifolium subterraneum L. – subterranean clover
Trifolium suffocatum L.
Trifolium sylvaticum Gérard
Trifolium tembense Fresen.
Trifolium tenuifolium
Trifolium thalii Vill.
Trifolium thompsonii C.V.Morton – Thompson's clover
Trifolium tomentosum L.
Trifolium × traplii
Trifolium triaristatum Bertero ex Colla
Trifolium trichocalyx A.Heller – Monterey clover
Trifolium trichocephalum M. Bieb.
Trifolium trichopterum Pančić
Trifolium tumens Steven ex M.Bieb.
Trifolium ukingense Harms
Trifolium uniflorum L.
Trifolium usambarense Taub.
Trifolium variegatum Nutt. – whitetip clover
Trifolium vavilovii Eig
Trifolium velebiticum Degen
Trifolium velenovskyi Vandas
Trifolium vernum Phil.
Trifolium vesiculosum Savi
Trifolium vestitum D.Heller & Zohary
Trifolium virginicum Small
Trifolium wentzelianum Harms
Trifolium wettsteinii Dörfl. & Hayek
Trifolium wigginsii J. M. Gillett
Trifolium willdenovii Spreng. − tomcat clover
Trifolium wormskioldii Lehm. – cow clover
Trifolium xanthinum

thumb|upright=1.1|Clover flowers beside [[Zarivar Lake in Iran]]

Distribution and habitat

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.

Ecology

thumb|A clover with a dewdrop|alt=A clover with a drop of dew in the middle

Bears, game animals, ruminants and birds forage for and eat clover. Increased soil nitrogen levels from the spreading use of clover were one of the main reasons why European agricultural production in 1880 was about 275% of the production in 1750. Fields of clover, used as forage and newly-invented silage, became an important part of the rural landscape; 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.

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,

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. although red clover contains phytoestrogens that may carry risks during pregnancy. The plant is a traditional Native American food, which is eaten both raw and after drying and smoking the roots. The seeds from the blossoms are used to make bread. It is also possible to make tea from the blossoms.

Clovers occasionally have four leaflets, instead of the usual three. These four-leaf clovers, like other rarities, are considered lucky. 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. The previous record holder, Shigeo Obara, had discovered an 18-leaf clover in 2002, a 21-leaf clover in 2008 and a 56-leaf clover in 2009, also in Japan.

A common idiom is "to be (or to live) in clover", meaning to live a carefree life of ease, comfort, or prosperity.

A common saying in surgery [regarding the appearance of wound after hemorrhoidectomy] is "If it looks like clover, the trouble is over; if it looks like dahlia, it’s surely a failure."

A cloverleaf interchange is named for the resemblance to the leaflets of a (four-leaf) clover when viewed from the air.

References

External links

Quattrofolium
Edibility of clover: Edible parts and visual identification of wild clover.
Nitrogen fixation