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,[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] 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.[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. [1]][White clover. Penn State University Extension. http://extension.psu.edu/plants/crops/forages/species/white-clover ]
Name
The genus name,
clover, 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".
Description
It is a
herbaceous,
perennial plant. It is low growing, with flowering
Flower heads of whitish florets, often with a tinge of pink or cream that may come on with the aging of the plant. The heads are generally wide, and are at the end of peduncles or inflorescence stalks.
[Richard H. Uva, Joseph C. Neal and Joseph M. Ditomaso, Weeds of The Northeast, (Ithaca, NY: Cornell University Press, 1997), Pp. 236-237.] The flowers are mostly visited by
and often by
. The leaves are
trifoliolate, smooth, elliptic to egg-shaped and long-petioled and usually with light or dark markings. The stems function as
, so white clover often forms mats, with the stems creeping as much as 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-leaf clover.
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 var. pipolina
-
Trifolium repens subsp. prostratum Nyman
Distribution
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.
Ancestry
Trifolium repens is an allotetraploid (2n = 4x = 32) of two diploid ancestors and exhibits disomic inheritance.
In order to increase genetic diversity for breeding, research is focused on finding these ancestors. Proposed ancestors of
T. repens include
T. nigrescens,
T. occidentale,
T. pallescens, and
T. 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
Forage
White clover has been described as the most important forage legume of the
temperate zones.
Symbiotic nitrogen fixation (up to of N,
although usually much less, e.g. about
[Andrae, John. 2004. White clover establishment and management guide. B 1251. Univ. of Georgia Extension.]) 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).
[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.] 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.
[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.] 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.
[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.] 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.
The O-methylated isoflavones formononetin and biochanin A play a role in arbuscular mycorrhiza formation on white clover roots,[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.] and foliar disease can stimulate production of estrogenic coumestans in white clover.[Adams, Norman R. "Detection of the effects of phytoestrogens on sheep and cattle." Journal of Animal Science 73, no. 5 (1995): 1509-1515.] However, while there have been a few reports of phytoestrogenic effects of white clover on grazing ruminants,[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.] which can contribute to competitive advantage.
Companion planting, green manure, and cover crops
White clover grows well as a companion plant among
,
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
mower and
grazing, and it can grow on many different types and pHs of soil (although it prefers
clay soils).
As a
legume 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
. 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.
[ The Organic Lawn Care Manual, Tukey, Storey Publishing. p 183.] For these reasons, it is often used as a
green manure and
cover crop.
Culinary uses
Besides making an excellent forage crop for
livestock,
its leaves and flowers are a valuable survival food: they are high in
, 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.
[Lee Allen Peterson, Edible Wild Plants, (New York City: Houghton Mifflin Company, 1977), P. 56.
] Native Americans ate some species raw.
Dried white clover flowers may also be smoked as a herbal alternative to tobacco.
Medicinal uses
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.
[Yadav, A. K. 2004. Anticestodal activity of Trifolium repens extract. Pharmaceutical Biology 42: 656-658.]
See also
Bibliography
External links
