Clover

Clover (Trifolium), or trefoil, is a genus of about 300 species of plants in the leguminous pea family Fabaceae. The genus has a cosmopolitan distribution; the highest diversity is found 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. The leaves are trifoliate (rarely 5- or 7-foliate), 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. Other closely related genera often called clovers include Melilotus (sweet clover) and Medicago (alfalfa or 'calvary clover'). The "shamrock" of popular iconography is sometimes considered to be young clover. The scientific name derives from the Latin tres, "three", and folium, "leaf", so called from the characteristic form of the leaf, which has three leaflets (trifoliate); hence the popular name trefoil. Clovers are used as food plants by the larvae of some Lepidoptera (butterfly and moth) species; see list of Lepidoptera that feed on clovers.

Contents 1 Cultivation 2 Symbolism and mythology 3 Selected species 4 Gallery 5 See also 6 References 7 External links

Cultivation

Several species 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 soiling, 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 grows in a great range of soils and climates; and it is appropriate for either pasturage or green composting.

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.

Clover sickness in more recent times may also be linked to pollinator decline; clovers are most efficiently pollinated by bumblebees, which have declined as a result of agricultural intensification.^[3] 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.

T. 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. T. 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 the last species. T. medium, meadow or zigzag clover, a perennial with straggling flexuous stems and rose-purple flowers, is of little agricultural value.

Other South African species are: T. 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; T. fragiferum, orange clover, with hot-grounded, globose, rose-purple heads and swollen calyxes; T. procumbens, hop trefoil, on dry pastures and roadsides, the heads of pale yellow flowers suggesting miniature hops; and the somewhat similar T. minus, common in pastures and roadsides, with smaller heads and small yellow flowers turning dark brown. It is a source of high protein.

Symbolism and mythology

Shamrock, the traditional Irish symbol, which according to legend was coined by Saint Patrick for the Holy Trinity, is commonly associated with clover, though sometimes with Oxalis species, which are also trifoliate (i.e., they have three leaves).

Clovers occasionally have leaves with 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 leaves, but these are rarer. The record for most leaves is 56, set in 10 May 2009.^[4] This beat the 21-leaf clover,^[5] a record set in June 2008 by the same man, who had also held the prior record Guinness World Record of 18.^[6]

A common idiom is "to be (live) in clover", meaning to live a carefree life of ease, comfort, or prosperity. This originally referred to the fact that clover is fattening to cattle.^[7]

The cloverleaf interchange is named for the resemblance to the leaves of a (four-leafed) clover when viewed from the air.

Selected species

The genus Trifolium currently has 245 recognized species:^[1]

Trifolium acaule A. Rich. Trifolium affine C. Presl Trifolium africanum Ser. Trifolium aintabense Boiss. & Hausskn. Trifolium albopurpureum Torr. & A. Gray Trifolium alexandrinum L. Trifolium alpestre L. Trifolium alpinum L. Trifolium amabile Kunth Trifolium ambiguum M. Bieb. Trifolium amoenum Greene, Showy Indian Clover Trifolium andersonii A. Gray Trifolium andinum Nutt. Trifolium andricum Lassen Trifolium angulatum Waldst. & Kit. Trifolium angustifolium L. Trifolium apertum Bobrov Trifolium argutum Banks & Sol. Trifolium arvense L., Hare's-foot clover Trifolium attenuatum Greene Trifolium aureum Pollich, Large Hop Trefoil Trifolium baccarinii Chiov. Trifolium badium Schreb. Trifolium barbeyi Gibelli & Belli Trifolium barbigerum Torr. Trifolium barnebyi (Isely) Dorn & Lichvar Trifolium batmanicum Katzn. Trifolium beckwithii W. H. Brewer ex S. Watson Trifolium bejariense Moric. Trifolium berytheum Boiss. & Blanche Trifolium bifidum A. Gray Trifolium bilineatum Fresen. Trifolium billardierei Spreng. Trifolium bivonae Guss. Trifolium blancheanum Boiss. Trifolium bocconei Savi Trifolium boissieri Guss. ex Soy.-Will. & Godr. Trifolium bolanderi A. Gray Trifolium brandegeei S. Watson Trifolium breweri S. Watson Trifolium brutium Ten. Trifolium buckwestiorum Isely Trifolium bullatum Boiss. & Hausskn. Trifolium burchellianum Ser. Trifolium calcaricum J. L. Collins & Wieboldt Trifolium calocephalum Fresen. Trifolium campestre Schreb., Hop Trefoil Trifolium canescens Willd. Trifolium carolinianum Michx. Trifolium caucasicum Tausch Trifolium caudatum Boiss. Trifolium cernuum Brot. Trifolium cheranganiense J. B. Gillett Trifolium cherleri L. Trifolium chilaloense Thulin Trifolium chilense Hook. & Arn. Trifolium chlorotrichum Boiss. & Balansa Trifolium ciliolatum Benth. Trifolium cinctum DC. Trifolium clusii Godr. & Gren. Trifolium clypeatum L. Trifolium congestum Guss. Trifolium constantinopolitanum Ser. Trifolium cryptopodium Steud. ex A. Rich. Trifolium cyathiferum Lindl., Cup clover Trifolium dalmaticum Vis. Trifolium dasyphyllum Torr. & A. Gray Trifolium dasyurum C. Presl Trifolium davisii M. Hossain Trifolium decorum Chiov. Trifolium depauperatum Desv. Trifolium dichotomum Hook. & Arn. Trifolium dichroanthoides Rech. f. Trifolium dichroanthum Boiss. Trifolium diffusum Ehrh. Trifolium dolopium Heldr. & Hausskn. ex Gibelli & Belli Trifolium douglasii House Trifolium dubium Sibth., Lesser Hop Trefoil Trifolium echinatum M. Bieb. Trifolium elgonense J. B. Gillett Trifolium eriocephalum Nutt. Trifolium eriosphaerum Boiss.

Trifolium erubescens Fenzl Trifolium euxinum Zohary Trifolium eximium Stephan ex Ser. Trifolium fragiferum L. Trifolium fucatum Lindl. Trifolium gemellum Pourr. ex Willd. Trifolium gillettianum Jacq.-Fél. Trifolium glanduliferum Boiss. Trifolium globosum L. Trifolium glomeratum L. Trifolium gordejevii (Kom.) Z. Wei Trifolium gracilentum Torr. & A. Gray Trifolium grandiflorum Schreb. Trifolium gymnocarpon Nutt. Trifolium haussknechtii Boiss. Trifolium haydenii Porter Trifolium heldreichianum (Gibelli & Belli) Hausskn. Trifolium hirtum All. Trifolium howellii S. Watson Trifolium hybridum L., Alsike Clover Trifolium incarnatum L., Crimson Clover Trifolium israeliticum Zohary & Katzn. Trifolium isthmocarpum Brot. Trifolium jokerstii Vincent & Rand. Morgan Trifolium juliani Batt. Trifolium kingii S. Watson Trifolium lanceolatum (J. B. Gillett) J. B. Gillett Trifolium lappaceum L. Trifolium latifolium (Hook.) Greene Trifolium latinum Sebast. Trifolium leibergii A. Nelson & J. F. Macbr. Trifolium lemmonii S. Watson Trifolium leucanthum M. Bieb. Trifolium ligusticum Balb. ex Loisel. Trifolium longidentatum Nábelek Trifolium longipes Nutt. Trifolium lucanicum Gasp. ex Guss. Trifolium lugardii Bullock Trifolium lupinaster L. Trifolium macilentum Greene Trifolium macraei Hook. & Arn. Trifolium macrocephalum (Pursh) Poir. Trifolium masaiense J. B. Gillett Trifolium mattirolianum Chiov. Trifolium mazanderanicum Rech. f. Trifolium medium L. Trifolium meduseum Blanche ex Boiss. Trifolium meironense Zohary & Lerner Trifolium michelianum Savi. Trifolium micranthum Viv. Trifolium microcephalum Pursh Trifolium microdon Hook. & Arn. Trifolium miegeanum Maire Trifolium monanthum A. Gray Trifolium montanum L. Trifolium mucronatum Willd. ex Spreng. Trifolium multinerve A. Rich. Trifolium mutabile Port. Trifolium nanum Torr. Trifolium neurophyllum Greene Trifolium nigrescens Viv. Trifolium noricum Wulfen Trifolium obscurum Savi Trifolium obtusiflorum Hook. & Arn. Trifolium ochroleucum Huds. Trifolium oliganthum Steud. Trifolium ornithopodioides L. Trifolium owyheense Gilkey Trifolium pachycalyx Zohary Trifolium palaestinum Boiss. Trifolium pallescens Schreb. Trifolium pallidum Waldst. & Kit. Trifolium pannonicum Jacq. Trifolium parnassi Boiss. & Spruner Trifolium parryi A. Gray Trifolium patens Schreb. Trifolium patulum Tausch Trifolium pauciflorum d'Urv. Trifolium petitianum A. Rich. Trifolium philistaeum Zohary Trifolium phitosianum N. Böhling et al. Trifolium phleoides Pourr. ex Willd.

Trifolium physanthum Hook. & Arn. Trifolium physodes Steven ex M. Bieb. Trifolium pichisermollii J. B. Gillett Trifolium pignantii Brongn. & Bory Trifolium pilczii Adamović Trifolium pilulare Boiss. Trifolium pinetorum Greene Trifolium plebeium Boiss. Trifolium plumosum Douglas Trifolium polymorphum Poir. Trifolium polyodon Greene Trifolium polyphyllum C. A. Mey. Trifolium polystachyum Fresen. Trifolium praetermissum Greuter et al. Trifolium pratense L., Red clover Trifolium prophetarum M. Hossain Trifolium pseudostriatum Baker f. Trifolium purpureum Loisel. Trifolium purseglovei J. B. Gillett Trifolium quartinianum A. Rich. Trifolium radicosum Boiss. & Hohen. Trifolium reflexum L. Trifolium repens L., Shamrock (white clover) Trifolium resupinatum L. Trifolium retusum L. Trifolium riograndense Burkart Trifolium roussaeanum Boiss. Trifolium rubens L. Trifolium rueppellianum Fresen. Trifolium salmoneum Mouterde Trifolium saxatile All. Trifolium scabrum L. Trifolium schimperi A. Rich. Trifolium scutatum Boiss. Trifolium sebastianii Savi Trifolium semipilosum Fresen. Trifolium setiferum Boiss. Trifolium simense Fresen. Trifolium sintenisii Freyn Trifolium siskiyouense J. M. Gillett Trifolium somalense Taub. Trifolium spadiceum L. Trifolium spananthum Thulin Trifolium spumosum L. Trifolium squamosum L. 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. Trifolium strictum L. Trifolium subterraneum L., Subterranean clover Trifolium suffocatum L. Trifolium sylvaticum Gérard ex Loisel. Trifolium tembense Fresen. Trifolium thalii Vill. Trifolium thompsonii C. V. Morton Trifolium tomentosum L. Trifolium triaristatum Bertero ex Colla Trifolium trichocalyx A. Heller 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. 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

Gallery

See also

• Cloverleaf quasar
• Cloverleaf interchange
• Four-leaf clover
• Sweet clover

References

•  This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed (1911). Encyclopædia Britannica (11th ed.). Cambridge University Press. 
• Quattrofolium

External links

• Edibility of clover: Edible parts and visual identification of wild clover.
• http://msucares.com/news/print/agnews/an04/040311.html Nitrogen fixation