Clover

Clover (Trifolium) is a genus of about 300 species of plants in the pea family Fabaceae. They are found chiefly in northern temperate regions, but also, like many other north temperate genera, on the mountains in the tropics. The plants are small annual or perennial herbs with trifoliate (rarely 5- or 7-foliate) leaves, with stipules adnate to the leaf-stalk, and heads or dense spikes of small red, purple, white, or rarely yellow flowers; the small, few-seeded pods are enclosed in the calyx. Eighteen species are native in Britain, and several are extensively cultivated as fodder-plants. The most widely cultivated clovers are White clover Trifolium repens and Red clover Trifolium pratense.

Other closely related genera often called clovers include Melilotus (sweet clover) and Medicago (alfalfa or 'calvary clover').

The scientific name derives from the Latin tres, three, and folium, a 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 species - see list of Lepidoptera which feed on Clovers.

A common idiom is "to be in clover", meaning to be living a carefree life of ease, comfort, or prosperity.

Cultivation

Clover, either sown alone or in mixture with rye-grass, 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 either for pasturage or soiling. Except on certain rich calcareous clay soils, it has now, however, become an exceedingly precarious crop. The seed germinates as freely as ever, when it is genuine, but this is unfortunately rare. In many areas, farmers are finding that the clover has either entirely disappeared by mid spring, or is found only in capricious patches here and there over the field. No satisfactory explanation of this "clover-sickness" has yet been given, nor has any certain remedy been discovered. However, one important fact is now well established; when crop rotations are managed so that clover does not recur at shorter intervals than eight years, it grows with much of its pristine vigour. The knowledge of this fact now determines many farmers in varying their rotation so as to secure this important end. At one time there was a somewhat prevalent belief that the introduction of beans into the rotation had a specific influence of a beneficial kind on the clover when it came next to be sown; but the true explanation seems to be that the beans operate favourably only by the incidental circumstance of almost necessarily lengthening the interval between the recurrences of clover.

Clover sickness may be linked to pollinator decline. Beekeepers are often in heavy demand from farmers with clover pastures, who want bees placed on their farms, as farmers observe the increased reseeding that occurs with increased bee activity.

Species

T. incarnatum, Crimson or Italian clover, though not hardy enough to withstand the climate of Scotland in ordinary winters, is a most valuable forage crop in England. It is sown as quickly as possible after the removal of a grain crop at the rate of 20-22 kg/ha. It is found to succeed better when only the surface of the soil is stirred by the scarifier and harrow than when a ploughing i1 given. It grows rapidly in spring, and yields an abundant crop of green food, peculiarly palatable to live stock. It is also suitable for making into hay. Only one cutting, however, can be obtained, as it does not shoot again after being mown.

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 British 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, Strawberry clover, with denselyflowered, 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. The last named is often called Shamrock. Specimens of shamrock and other clovers are not infrequently found with four leaflets, and, like other rarities, are considered lucky.

Uses

Clovers are a valuable survival food, as they are high in protein, widespread, and abundant. They are not easy to digest raw, but this can be easily fixed by boiling for 5-10 minutes. Dried flowerheads and seedpods can also be ground up into a nutritious flour and mixed with other foods. Dried flowerheads also steeped in hot water for a healthy, tasty tea.