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Clover

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Not to be confused with Clove.
"Alsike" and "Trifolium" redirect here. For the Swedish locality, see Alsike, Sweden. For the Canadian locality, see Alsike, Alberta. For the trematode parasite, see Cladocystis trifolium. For other uses, see Clover (disambiguation).

Clover
Trifolium repens (white clover)
Scientific classification Edit this 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
subg. Trifolium

sect. Glycyrrhizum
sect. Involucrarium
sect. Lupinaster
sect. Paramesus
sect. Trichocephalum
sect. Trifoliastrum
sect. Trifolium
sect. Vesicastrum
Synonyms

Amoria C. Presl[2]
Bobrovia A. P. Khokhr.[2]
Chrysaspis Desv.[2]
Lupinaster Fabr.[2]
Ursia Vassilcz.[2]
Xerosphaera Soják[2]

Clover or trefoil are common names for plants of the genus Trifolium (from Latin tres 'three' + folium 'leaf'), consisting of about 300 species of flowering plants in the legume or pea family Fabaceae originating in Europe. The genus has a cosmopolitan distribution with 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 cm tall. The leaves are trifoliate (rarely quatrefoiled; see four-leaf clover), monofoil, bifoil, cinquefoil, hexafoil, septfoil, etcetera, 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).

Cultivation

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]

Colorful flowers of clovers beside Zarivar Lake in Iran
White clover

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]

Uses

Clover is foraged by wildlife, including bears, game animals, and birds. Native Americans ate the plants raw and cooked, drying and smoking the roots. The seeds from the blossoms were used to make bread.[7] It is also possible to make tea from the blossoms.[7]

Symbolism

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.[8]

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 clovers outer leaf structure varies in physical orientation. The record for most leaflets is 56, set on 10 May 2009.[9] This beat the "21-leaf clover",[10] a record set in June 2008 by the same discoverer, who had also held the prior Guinness World Record of 18.[11]

A common idiom is "to be (or to live) in clover", meaning to live a carefree life of ease, comfort, or prosperity.[12]

A cloverleaf interchange is named for the resemblance to the leaflets of a (four-leaf) clover when viewed from the air.[13]

Phylogeny

The first extensive classification of Trifolium was done by Zohary and Heller in 1984. They divided the genus into eight sections: Lotoidea, Paramesus, Mistyllus, Vesicamridula, Chronosemium, Trifolium, Trichoecephalum, and Involucrarium, with Lotoidea placed most basally.[14] 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.[15] 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.[16][17]

Selected species

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

See also

References

  1. ^ a b "Species Nomenclature in GRIN". Archived from the original on 2008-10-14. Retrieved 2010-08-04.
  2. ^ a b c d e f "Genus Nomenclature in GRIN". Archived from the original on 2015-09-24. Retrieved 2010-07-09.
  3. ^ a b c d e f  One or more of the preceding sentences incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Clover". Encyclopædia Britannica. Vol. 6 (11th ed.). Cambridge University Press. p. 561.
  4. ^ Bumbles make beeline for gardens, study suggests Archived 2018-05-18 at the Wayback Machine Retrieved 27 November 2010.
  5. ^ Oertel, Everett (1967). Beekeeping in the United States. U.S. Department of Agriculture. p. 16. Archived from the original on 2023-01-16. Retrieved 2022-03-11.
  6. ^ Isobe, S.; Sawai, A.; Yamaguchi, H.; Gau, M.; Uchiyama, K. (2002). "Breeding potential of the backcross progenies of a hybrid between Trifolium medium × T. pratense to T. pratense". Canadian Journal of Plant Science. 82 (2): 395–399. doi:10.4141/P01-034.
  7. ^ a b Angier, Bradford (1974). Field Guide to Edible Wild Plants. Harrisburg, PA: Stackpole Books. p. 60. ISBN 0-8117-0616-8. OCLC 799792.
  8. ^ "Shamrock (Oxalis)". Fine Gardening. Archived from the original on March 1, 2017. Retrieved February 28, 2017.
  9. ^ "Most Leaves on a Clover". Guinness World Records. 2011. Archived from the original on 2015-03-19. Retrieved 2011-04-23.
  10. ^ Clover Sets Record. Neatorama. Retrieved on 2008-12-07 from http://www.neatorama.com/2008/06/11/21-leaf-clover-sets-record 21-leaf. Archived July 22, 2009, at the Wayback Machine
  11. ^ "Most leaves on a clover". Guinness World Records. Archived from the original on March 25, 2008. Retrieved 22 December 2016.
  12. ^ "Cambridge Dictionary". Cambridge Dictionary. June 26, 2021. Archived from the original on 2015-10-04. Retrieved June 26, 2021.
  13. ^ Pollard, Michael (1986). Travel by Road and Rail. Independence, Ohio: Schoolhouse Press. p. 31. ISBN 9780808610403.
  14. ^ Zohary, Michael (1984). The genus Trifolium. Heller, D. Jerusalem: Israel Academy of Sciences and Humanities. ISBN 978-9652080561. OCLC 11057949.
  15. ^ Ellison, Nick W.; Liston, Aaron; Steiner, Jeffrey J.; Williams, Warren M.; Taylor, Norman L. (2006). "Molecular phylogenetics of the clover genus (Trifolium—Leguminosae)". Molecular Phylogenetics and Evolution. 39 (3): 688–705. doi:10.1016/j.ympev.2006.01.004. PMID 16483799.
  16. ^ Vižintin, Liliana; Javornik, Branka; Bohanec, Borut (2006). "Genetic characterization of selected Trifolium species as revealed by nuclear DNA content and ITS rDNA region analysis". Plant Science. 170 (4): 859–866. doi:10.1016/j.plantsci.2005.12.007.
  17. ^ Watson, L. E.; Sayed-Ahmed, H.; Badr, A. (2000-09-01). "Molecular phylogeny of Old WorldTrifolium (Fabaceae), based on plastid and nuclear markers". Plant Systematics and Evolution. 224 (3–4): 153–171. doi:10.1007/BF00986340. ISSN 0378-2697. S2CID 45350663.
  18. ^ "Detox and Cleansing". 2014-12-24. Archived from the original on March 6, 2016. Retrieved March 12, 2016.
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