Trifolium
(from trees, three, and folium, a leaf; most of the species have trifoliolate leaves). Clover; Trefoil. Including Lupinaster and Pentaphyllon. ORD. Leguminosae. A large genus (nearly 280 species have been described, of which, probably, not more than 150 are really distinct) of hardy, annual or perennial herbs, copiously dispersed over the temperate and sub-tropical regions of the Northern hemisphere, a few being also found in the mountains of tropical America, Africa, and extra-tropical South America. Flowers often purple, red, or white, rarely yellow, spicate, capitate, umbellate, or rarely solitary; calyx teeth or lobes sub-equal, or the lower ones longer; petals often marcescent, all long-clawed, or the four lower ones more or less adnate with the staminal tube; standard oblong or ovate; wings narrow; keel shorter than the wings, obtuse; stamens diadelphous. Pod oblong and sub-terete, or obovate-compressed, indehiscent. Leaves digitately three, rarely five or seven, foliolate, sometimes pinnately three or very rarely five-foliolate; stipules adnate with the petioles. This genus embraces several important fodder-plants. Eighteen species are included within the British Flora, viz., T. arvense (Hare's-foot Clover), T. Bocconi, T. filiforme (Yellow Suckling Clover), T. fragiferum (Strawberry Clover), T. glomeratum, T. incarnatum (Crimson or Carnation Clover), T. maritimum, T. medium (Cow Grass; Meadow or Zigzag Clover), T. minus, T. ochroleucum, T. pratense (Red or Broad-leaved Clover; Marl-grass), T. procumbens (Hop Trefoil), T. repens (White or Dutch Clover; Shamrock), T. scabrum, T. striatum (Knotted Clover), T. strictum, T. subterraneum, and T. suffocatum (Sand Clover); and T. hybridum (Alsike or Bastard Clover) has become naturalised. Four-leaved Shamrocks and other Clovers are considered "lucky," as being rare, but are by no means unfrequently met with. Few of the species of Trifolium boast of much horticultural merit; the selection given below embraces all that call for description here. All thrive in common garden soil. The annuals and biennials may be increased by seeds, and the perennials by divisions. Except where otherwise stated, the under-mentioned plants are perennials. T. alpestre (alpine).* Owl-headed Clover. fl. purple; lower calyx segment longer than the gamopetalous corolla, the rest short and tooth-like; heads globose. June and July. l., leaflets lanceolate, coriaceous, ciliately serrulated; stipules narrow, nearly sessile, long. Stem erect, simple. h. 6in. to 12in. Alps of Europe and Western Asia, 1789. (B. M. 2779.) T. caeruleum (blue). A synonym of Trigonella caerulea. T. canescens (hoary). fl. cream-coloured; calyx smooth, the lowest segment a little longer than the rest; corolla gamopetalous, much longer than the calyx segments; heads terminal, large, oblong, nearly sessile. May and June. l., leaflets obovate, emarginate, villous; stipules lanceolate-subulate. Stems ascending, adpressedly hairy. Cappadocia, &c., 1803. (B. M. 1168.) T. fimbriatum (fringed). fl. purple; calyx teeth spiny, half as long as the slender corolla; heads 1in. in diameter. September and October. l., leaflets oblong or slightly cuneate, 1in. or more in length, conspicuously fringed with spinulose-setaceous teeth. Stems long and thick, prostrate, glabrous. North America, 1825. (B. R. 1070; L. B. C. 1421.) T. fucatum (painted). fl. cream-colour mixed with red; corolla many times longer than the calyx; heads 1in. to 2in. in diameter, somewhat hemispherical, few-flowered; peduncles axillary, mostly longer than the leaves. June. l., leaflets roundish-cuneiform, sharply denticulate, rather thick; stipules large, entire, mucronate. h. 6in. California, 1824. Annual. (B. R. 1883.) T. hybridum (hybrid). Alsike or Bastard Clover. fl. white or rosy, 1/3in. long, drooping; heads axillary, peduncled, globose, 3/4in. to 1in. in diameter. June to August. l. on long petioles; leaflets obovate or oblong, 1/2in. to 1 1/2in. long, toothed; stipules oblong, with triangular tips. Stems 2in. to 10in. long, flexuous. Europe, &c. (B. M. 3702.) T. incarnatum (flesh-coloured). Crimson Clover. fl. bright scarlet, 1/2in. long; calyx hairy; heads peduncled, terminal, ovoid or cylindric, 1in. to 2in. in diameter. June and July. l. on short petioles; leaflets broadly obovate or obcordate, 3/4in. to 1 1/2in. long; stipules obtuse. Stems rather slender, clothed with spreading hairs. h. 1ft. South Europe, 1640. Annual. (B. M. 328.) T. Lupinaster (Lupinaster).* Bastard Lupine. fl. purple, large, the wings and keel paler than the standard; heads pedunculate, bractless, umbellate. June to August. l. sessile; leaflets five, linear-lanceolate, sharply toothed, mucronate; stipules broad, acuminate. h. 1ft. to 1 1/2ft. Siberia, 1741. (B. M. 879.) albiflorum is a white-flowered form.
T. olympicum (Olympic). fl. yellowish; calyx hairy; standard very long; spikes oblong, solitary. July. l., leaflets hairy, elliptic-lanceolate, entire; stipules subulate, sheathing. Stem erect, hairy. h. 1ft. Mount Olympus, 1817. (B. M. 2790.) T. reflexum (reflexed). Buffalo Clover. fl. handsome; standard rose-red, broadly ovate; wings and keel white; heads sub-umbellate, dense; peduncles about twice the length of the heads. April to June. l., leaflets obovate or obovate-oblong, sometimes emarginate, crenulate-serrulate; stipules leafy, acuminate. Stem ascending or decumbent, 1ft. to 1 1/2ft. long North America, 1794. Annual. (B. M. 3471.) T. rubens (reddish). fl. carmine or purple-red; heads peduncled, ovoid, large. Summer. l. stalked; leaflets long, narrow; stipules large. Stems erect. h. 1ft. Central and South Europe. (R. G. 1886, p. 243.) T. spadiceum (chestnut-brown). Brown Clover. fl. yellow; standard slightly ferruginous, obcordate; heads ovoid, pedunculate. June to August. l. stalked; leaflets oblong-ovate, sessile, denticulated; stipules leafy, acuminate. Stem erect, 6in. high. Europe, 1778. (B. M. 557.) T. uniflorum (one-flowered).* fl. axillary, solitary, on short peduncles; corolla very long, the standard blue, the wings and keel purple. May to September. l., leaflets three, ovate, acuminate, toothed, nerved; stipules sheathing, long-acuminate. Stems very short. Syria, &c., 1800. Plant tufted, creeping. (L. B. C. 1882; S. B. F. G. ser. ii. 200.) The form Sternbergianum has white flowers.
T. vesiculosum (bladdery-calyxed). fl., reddish; calyx scarious, inflated, the segments subulate, much shorter than the corolla; heads ovate, thick, on long peduncles. June and July. l., leaflets lanceolate, acute, sharply serrulated; stipules narrow, long-acuminate. Stems erect, firm, 9in. high. South Europe, 1805. (B. R. 1408.)