TRIFOLIUM, in botany, trefoil, a ge nus of the Diadelphia Decandria class and order. Natural order of Papllionacem or Leguminosx. EsSential character : flow ers in a head.; legume scarcely longer than the calyx ; nectary opening, There are fifty-one speCies. T. of ficinale or inelilot, has naked racemeus pods, dispermous, wrinkly, and acute, ivith an erect stalk. It grows in corn fields, and by the way sides, but is not common. The stalk is erect, firm, striat ed, branched, and two or three feet high ; the leaves ternate, smooth, obtusely oval, and serrated ; the flowers are small, yel low, pendulous, and grow in long close spikes at the tops of the branches ; the pod is very short, turgid, transversely wrinkled, pendulous, and contains either one or two seeds. The plant has a very peculiar strong scent, and disagreeable, bitter, acrid taste, bid such, however, as is not disagreeable to cattle. The flowers are sweet scented. It communicates a loathsome flavour to wheat and other grain, so as to render it unfit for making bread. T.'repcns, white creeping trefbil,
or Dutch clover, has a creeping stalk, its flower-gathered into an umbellar head, and its pods tetraspermous. it is very_ common in fields and pastures. It is well known to be excellent fodder for cattle ; and the 'leaves are a good rustic hygro Meter, as they are always relaxed and 'flaccid in dry weather, but erect in moist or rainy. T. purple, or red clo ver, is distinguished by &rise spikes, unequal corollas, by bearded stipulas, as cending stalks, and by the calyx having four equal teeth. The red clover is com mon in meadows and pastures, and is the species which is generally cultivated as food for cattle. It abounds in every part of Europe, in North America, and even in Siberia. It delights most in rich, moist, and sunny places, yet flourishes in those that are dry, barren, and shady. See Hes tIANratr.