Белый клевер: описание, распространение и адаптация к городской среде

Flowering plant, bean family Fabaceae
Speciesbox
| name = White clover
| image = Trifolium repens white clover on way from Govindghat to Gangria at Valley of Flowers National Park during LGFC VOF 2019 (1). jpg
| genus = Trifolium
| species = repens
| authority = L.
| synonyms ref = 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 [[:wikt:tres, "three", and [[:wikt: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, [[:wikt:repens, is Latin for "creeping".

It is a herbaceous, perennial plant. It is low growing, with flowering 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. 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 a year, and rooting at the nodes.</small>

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 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.

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 ) 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. The O methylated isoflavones 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, which can contribute to competitive advantage.

White clover grows well as a companion plant among lawns, grain crops, pasture grasses, and vegetable rows. 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'.