Trifolium repens, the white clover, is a herbaceous perennial plant in the bean family Fabaceae (otherwise known as Leguminosae). 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 (lawns and gardens) 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 (but sometimes to smaller varieties), and 'ladino clover' is applied to large varieties.
The genus name, Trifolium, derives from the Latin tres, "three", and folium, "leaf", so called from the characteristic form of the leaf, which almost always has three leaflets (trifoliolate); hence the popular name "trefoil". The species name, repens, is Latin for "creeping".
It is a herbaceous, perennial plant. It is low growing, with heads of whitish flowers, often with a tinge of pink or cream that may come on with the aging of the plant. The heads are generally 1.5–2 centimetres (1⁄2–3⁄4 in) wide, and are at the end of 7 centimetres (2+3⁄4 in) peduncles or inflorescence stalks. The flowers are mostly visited by bumblebees and often by honey bees. The leaves are trifoliolate, smooth, elliptic to egg-shaped and long-petioled and usually with light or dark markings. The stems function as stolons, so white clover often forms mats, with the stems creeping as much as 18 cm (7 in) a year, and rooting at the nodes. The leaves form the symbol known as shamrock. Almost always, a white clover will be trifoliolate. However, one can, but only sometimes, possess four or more leaflets.
Varieties and subspecies
- Trifolium repens subsp. macrorrhizum (Boiss.) Ponert
- Trifolium repens var. nevadense (Boiss.) C.Vicioso
- Trifolium repens var. ochranthum K.Maly
- Trifolium repens var. orbelicum (Velen.) Fritsch
- Trifolium repens var. orphanideum (Boiss.) Boiss.
- Trifolium repens subsp. prostratum Nyman
It is native in Europe and Central Asia, ubiquitous throughout the British Isles, introduced in North America, South Africa, Australia, New Zealand, Japan and elsewhere, and globally cultivated as a forage crop.
White clover has been used as a model organism for global research into ecology and urban evolution. As part of the Global Urban Evolution Project (GLUE) scientists from 26 countries examined the production of cyanide by over 110,000 clover plants from 160 cities. Cyanide can be useful to clover plants as a deterrent to herbivores. Analyzing urban-rural differences, scientists found that cyanide production tended to increase with distance from the center of cities, suggesting that clover populations were adapting to factors commonly found in urban centers worldwide. Possible factors could include temperature (freezing is related to cyanide content), herbivory pressures, and drought stress. As clover habitats, the downtowns of cities may more closely resemble other far-flung cities than nearby rural areas.
Trifolium repens is a tetraploid (4n=32) with two diploid ancestors. In order to increase genetic diversity for breeding, research is focused on finding these ancestors. Proposed ancestors of Trifolium repens include Trifolium nigrescens, Trifolium occidentale, Trifolium pallescens, and Trifolium uniflorum. Additionally, it is possible that one of the diploid ancestors has yet to be analyzed, either because it has not been discovered or is extinct.
Cultivation and uses
White clover has been described as the most important forage legume of the temperate zones. Symbiotic nitrogen fixation (up to 545 kilograms per hectare per year (486 lb/acre/a) of N, although usually much less, e.g. about 110 to 170 kilograms per hectare per year (98 to 152 lb/acre/a)) in root nodules of white clover obviates synthetic nitrogen fertilizer use for maintaining productivity on much temperate zone pasture land. White clover is commonly grown in mixtures with forage grasses, e.g. perennial ryegrass (Lolium perenne). Such mixtures can not only optimize livestock production, but can also reduce the bloat risk to livestock that can be associated with excessive white clover in pastures. Such species mixtures also tend to avoid issues that could otherwise be associated with cyanogenic glycosides (linamarin and lotaustralin) intake on pure or nearly pure stands of some white clover varieties. However, problems do not inevitably arise with grazing on monocultures of white clover, and superior ruminant production is sometimes achieved on white clover monocultures managed to optimize sward height.
Formononetin and biochanin A play a role in arbuscular mycorrhiza formation on white clover roots, and foliar disease can stimulate production of estrogenic coumestans in white clover. However, while there have been a few reports of phytoestrogenic effects of white clover on grazing ruminants, these have been far less common than such reports regarding some varieties of subterranean clover (Trifolium subterraneum) and red clover (Trifolium pratense). Among forage plants, some white clover varieties tend to be favored by rather close grazing, because of their stoloniferous habit, which can contribute to competitive advantage.
Companion planting, green manure, and cover crops
White clover grows well as a companion plant among lawns, grain crops, pasture grasses, and vegetable rows. It is often added to lawn seed mixes, as it is able to grow and provide green cover in poorer soils where turfgrasses do not perform well. White clover can tolerate close mowing and grazing, and it can grow on many different types and pHs of soil (although it prefers clay soils). As a leguminous and hardy plant, it is considered to be a beneficial component of natural or organic pasture management and lawn care due to its ability to fix nitrogen and out-compete weeds. Natural nitrogen fixing reduces leaching from the soil and by maintaining soil health can reduce the incidence of some lawn diseases that are enhanced by the availability of synthetic fertilizer. For these reasons, it is often used as a green manure and cover crop.
Besides making an excellent forage crop for livestock, its leaves and flowers are a valuable survival food: they are high in proteins, and are widespread and abundant. The fresh plants have been used for centuries as additives to salads and other meals consisting of leafy vegetables. They are not easy for humans to digest raw, but, this is however easily fixed by boiling the harvested plants for 5–10 minutes. Native Americans ate some species raw. Dried white clover flowers may also be smoked as a herbal alternative to tobacco.
In India, T. repens is considered a folk medicine against intestinal helminthic worms, and an experimental in-vivo study validated that the aerial shoots of T. repens bear significant anticestodal (anti-tapeworm) properties.
Trifolium means 'trefoil' (three-lobed leaves); this is Pliny’s name for trifoliate plants.
Repens means 'creeping' or 'stoloniferous'.
- ^ a b "Trifolium repens L. — The Plant List". theplantlist.org.
- ^ USDA, NRCS (n.d.). "Trifolium repens". The PLANTS Database (plants.usda.gov). Greensboro, North Carolina: National Plant Data Team. Retrieved 15 December 2015.
- ^ a b Clapham, A.R., Tutin, T.G. and Warburg., E.F. 1968. Excursion Flora of the British Isles. Cambridge University Press. ISBN 0-521-04656-4
- ^ "Altervista Flora Italiana, Trifoglio strisciante, Weißklee, vitklöver, Trifolium repens L". Luirig.altervista.org. Retrieved 2018-07-16.
- ^ "Weeds of Australia: Trifolium repens".
- ^ Böcher, T. W. 1978. Greenlands Flora 326 pp.
- ^ Duchen, P. & S. G. Beck. 2012. Estudio taxonómico de las Leguminosas del Parque Nacional Area Natural de Manejo Integrado (PN-ANMI) Cotapata, La Paz-Bolivia. Revista de la Sociedad Boliviana de Botánica 6(1): 13–51.
- ^ Correa A., M.D., C. Galdames & M. Stapf. 2004. Catálogo de las Plantas Vasculares de Panamá 1–599. Smithsonian Tropical Research Institute, Panamá
- ^ Marticorena, C. & M. Quezada. 1985. Catálogo de la Flora Vascular de Chile. Gayana. Botánica 42: 1–157.
- ^ Porsild, A. E. & W. Cody. 1980. Checklist of the Vascular Plants of the Northwest Territories Canada i–viii, 1–607. National Museum of Natural Sciences, Ottawa
- ^ Barnes, R. F., C. J. Nelson, M. Collins, and K. J. Moore (eds.). 2003. Forages: an introduction to grassland agriculture. Vol. 1. 6th ed. Blackwell Publishing. 556 pp.
- ^ Henning, J. C. and H. N. Wheaton. 1993. White, ladino and sweet clover. G4639. U. Missouri Extension. http://extension.missouri.edu/p/G4639
- ^ Rasnake, M., G. D. Lacefield, J. C. Henning, N. L. Taylor and D. C. Ditsch. Growing white clover in Kentucky. Univ. Kentucky. AGR-93. 
- ^ White clover. Penn State University Extension. http://extension.psu.edu/plants/crops/forages/species/white-clover
- ^ a b c d Richard H. Uva, Joseph C. Neal and Joseph M. Ditomaso, Weeds of The Northeast, (Ithaca, NY: Cornell University Press, 1997), Pp. 236-237.
- ^ Van Der Kooi, C. J.; Pen, I.; Staal, M.; Stavenga, D. G.; Elzenga, J. T. M. (2015). "Competition for pollinators and intra-communal spectral dissimilarity of flowers". Plant Biology. 18 (1): 56–62. doi:10.1111/plb.12328. PMID 25754608.
- ^ "BSBI Online Atlas of the British Flora". Retrieved 16 June 2018.
- ^ Bender, Eric (21 March 2022). "Urban evolution: How species adapt to survive in cities". Knowable Magazine. Annual Reviews. doi:10.1146/knowable-031822-1. Retrieved 31 March 2022.
- ^ Santangelo, James S.; Ness, Rob W.; Cohan, Beata; et al. (18 March 2022). "Global urban environmental change drives adaptation in white clover". Science. 375 (6586): 1275–1281. Bibcode:2022Sci...375.1275S. doi:10.1126/science.abk0989. hdl:10026.1/19203. ISSN 0036-8075. PMID 35298255. S2CID 247520798. Retrieved 1 April 2022.
- ^ Diamond, Sarah E.; Martin, Ryan A. (2 November 2021). "Evolution in Cities". Annual Review of Ecology, Evolution, and Systematics. 52 (1): 519–540. doi:10.1146/annurev-ecolsys-012021-021402. ISSN 1543-592X. S2CID 239646134. Retrieved 1 April 2022.
- ^ a b 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.
- ^ Williams, Warren M.; Ellison, Nicholas W.; Ansari, Helal A.; Verry, Isabelle M.; Hussain, S. Wajid (2012-04-24). "Experimental evidence for the ancestry of allotetraploid Trifolium repens and creation of synthetic forms with value for plant breeding". BMC Plant Biology. 12: 55. doi:10.1186/1471-2229-12-55. ISSN 1471-2229. PMC 3443075. PMID 22530692.
- ^ Williams, W. M.; Ansari, H. A.; Hussain, S. W.; Ellison, N. W.; Williamson, M. L.; Verry, I. M. (2008-01-01). "Hybridization and Introgression between Two Diploid Wild Relatives of White Clover, Trifolium nigrescens Viv. and T. occidentale Coombe". Crop Science. 48 (1): 139–148. doi:10.2135/cropsci2007.05.0295. ISSN 1435-0653.
- ^ Badr, A.; El-Shazly, H. H.; Mekki, L. (2012-06-01). "Genetic diversity in white clover and its progenitors as revealed by DNA fingerprinting". Biologia Plantarum. 56 (2): 283–291. doi:10.1007/s10535-012-0088-0. ISSN 0006-3134. S2CID 14983555.
- ^ Hand, Melanie L.; Ponting, Rebecca C.; Drayton, Michelle C.; Lawless, Kahlil A.; Cogan, Noel O. I.; Brummer, E. Charles; Sawbridge, Timothy I.; Spangenberg, German C.; Smith, Kevin F. (2008-10-01). "Identification of homologous, homoeologous and paralogous sequence variants in an outbreeding allopolyploid species based on comparison with progenitor taxa". Molecular Genetics and Genomics. 280 (4): 293–304. doi:10.1007/s00438-008-0365-y. ISSN 1617-4615. PMID 18642031. S2CID 24487483.
- ^ Elgersma, Anjo, and Jan Hassink. "Effects of white clover (Trifolium repens L.) on plant and soil nitrogen and soil organic matter in mixtures with perennial ryegrass (Lolium perenne L.)." Plant and Soil 197, no. 2 (1997): 177-186.
- ^ Carlsson, G., and K. Huss-Danell. "Nitrogen fixation in perennial forage legumes in the field." Plant and Soil 253, no. 2 (2003): 353-372.
- ^ Andrae, John. 2004. White clover establishment and management guide. B 1251. Univ. of Georgia Extension.
- ^ Ulyatt, M. J., D. J. Thomson, D. E. Beever, R. T. Evans, and M. J. Haines. "The digestion of perennial ryegrass (Lolium perenne cv. Melle) and white clover (Trifolium repens cv. Blanca) by grazing cattle." British Journal of Nutrition 60, no. 01 (1988): 137-149.
- ^ Evans, D. R., and T. A. Williams. "The effect of cutting and grazing managements on dry matter yield of white clover varieties (Trifolium repens) when grown with S23 perennial ryegrass." Grass and Forage Science 42, no. 2 (1987): 153-159.
- ^ Moseley, G., and J. R. Jones. "The physical digestion of perennial ryegrass (Lolium perenne) and white clover (Trifolium repens) in the foregut of sheep." British Journal of Nutrition 52, no. 02 (1984): 381-390.
- ^ Wolfe, E. C., and Alec Lazenby. "Bloat incidence and liveweight gain in beef cattle on pastures containing different proportions of white clover (Trifolium repens)." Animal Production Science 12, no. 55 (1972): 119-125.
- ^ Crush, J. R., and J. R. Caradus. "Cyanogenesis potential and iodine concentration in white clover (Trifolium repens L.) cultivars." New Zealand Journal of Agricultural Research 38, no. 3 (1995): 309-316.
- ^ Orr, R. J., A. J. Parsons, P. D. Penning, and T. T. Treacher. "Sward composition, animal performance and the potential production of grass/white clover swards continuously stocked with sheep." Grass and Forage Science 45, no. 3 (1990): 325-336.
- ^ Siqueira, J. O., G. R. Safir, and M. G. Nair. "Stimulation of vesicular‐arbuscular mycorrhizal formation and growth of white clover by flavonoid compounds." New Phytologist 118, no. 1 (1991): 87-93.
- ^ a b Adams, Norman R. "Detection of the effects of phytoestrogens on sheep and cattle." Journal of Animal Science 73, no. 5 (1995): 1509-1515.
- ^ Lane, L. A., J. F. Ayres and J. V. Lovett. "The pastoral significance, adaptive characteristics, and grazing value of white clover (Trifolium repens L.) in dryland environments in Australia: a review." Animal Production Science 40, no. 7 (2000): 1033-1046.
- ^ Caradus, J. R. "Genetic diversity within white clover (Trifolium repens L.)." In Proceedings Agronomy Society of NZ, vol. 24, p. 2. 1994.
- ^ The Organic Lawn Care Manual, Tukey, Storey Publishing. p 183.
- ^ Coladonato, Milo (1993). "Trifolium repens". U.S. Department of Agriculture, Forest Service, Rocky Mountain Research Station, Fire Sciences Laboratory. Retrieved 2015-07-26.
- ^ Lee Allen Peterson, Edible Wild Plants, (New York City: Houghton Mifflin Company, 1977), P. 56.
- ^ Reiner, Ralph E. (1969). Introducing the Flowering Beauty of Glacier National Park and the Majestic High Rockies. Glacier Park, Inc. p. 10.
- ^ "Clover - White". Foraging Texas. Retrieved 2018-07-16.
- ^ Yadav, A. K. 2004. Anticestodal activity of Trifolium repens extract. Pharmaceutical Biology 42: 656-658.
- ^ a b Gledhill, David (2008). "The Names of Plants". Cambridge University Press. ISBN 9780521866453 (hardback), ISBN 9780521685535 (paperback). pp 328, 386
Tangpu, V., Temjenmongla & Yadav, A. K. 2004. Anticestodal activity of Trifolium repens extract. Pharmaceutical Biology 42: 656–658.
- Flora of Africa
- Flora of Europe
- Flora of Asia
- Medicinal plants of Europe
- Medicinal plants of Africa
- Garden plants of Europe
- Nitrogen-fixing crops
- Plants described in 1753
- Plants used in traditional Native American medicine
- National symbols of the Republic of Ireland
- Melliferous flowers
- Taxa named by Carl Linnaeus