FABACEAE

LEGUME FAMILY

Annual to tree
Leaves generally compound, alternate, stipuled; leaflets generally entire
Inflorescence: generally raceme, spike, umbel or head; flowers sometime 1–2 in axils
Flowers generally bisexual, generally bilateral; hypanthium generally flat or cup-like; sepals generally 5, fused; petals generally 5, free, or the 2 lower ± fused; stamens 1–many, often 10 with 9 filaments at least partly fused, 1 (uppermost) free; pistil 1, ovary superior, generally 1-chambered, ovules 1–many, style, stigma 1
Fruit: legume, sometimes including a stalk-like base above receptacle, dehiscent, or indehiscent and breaking into 1-seeded segments, or indehiscent, 1-seeded, and achene-like
Seeds 1–several, often ± reniform, generally hard, smooth
Genera in family: ± 650 genera, 18,000 species: worldwide; with grasses, requisite in agriculture and most natural ecosystems. Many cultivated, most importantly Arachis , peanut; Glycine , soybean; Phaseolus , beans; Medicago ; Trifolium ; and many orns
Reference: [Polhill & Raven (eds) 1981 Advances in legume systematics; Allen & Allen 1981 Leguminosae]
Family description and key to genera by Duane Isely.

TRIFOLIUM

CLOVER

Duane Isely

Annual or perennial herb, unarmed
Leaves generally palmately compound; stipules conspicuous, partly fused to petiole; leaflets generally 3, sometimes 5–9, ± serrate or dentate
Inflorescence: raceme (often umbel-like), head, or spike, axillary or terminal, generally many-flowered, often involucred, generally peduncled; flowers bracted or not
Flower generally spreading to erect, often becoming reflexed; corolla generally purple to pale lavender, sometimes yellow, persistent after flower; 9 filaments fused, 1 free
Fruit generally indehiscent, but often breaking, short, plump, generally included in corolla; base often stalk-like
Seeds 1–6
Etymology: (Latin: 3 leaves)
Reference: [Gillett 1980 Can J Bot 58:1425–1558; Zohary & Heller 1984 Genus Trifolium]

Native

T. bifidum A. Gray

Annual, glabrous or sparsely fine-hairy
Stem sprawling to erect
Leaves cauline; stipules short-awned; leaflets 1–2 cm, oblanceolate to obovate, tip generally notched
Inflorescence head- or umbel-like, 7–15 mm wide, 5–many-flowered; axis tip often short-exserted; pedicel 1–2 mm; flowers becoming reflexed
Flower: calyx 3.5–5 mm, tube glabrous, 0.8–1.4 mm, lobes >> tube, ± 0.2 mm wide at base, awn-like, bristle-tipped, often with a few fine hairs; corolla 6–9 mm, dull yellow to pink-purple
Seeds 1–2
Chromosomes: 2n=16
Ecology: Open, grassy areas, oak chaparral, forests
Elevation: < 1000 m.
Bioregional distribution: California Floristic Province (except High Sierra Nevada, Tehachapi Mountain Area)
Distribution outside California: to Washington

Native

var. bifidum

Leaf: leaflet length 2.5–5.5 X width, tip notched 1/10–4/10 length, otherwise generally entire
Ecology: Habitats of sp.
Elevation: < 600 m.
Bioregional distribution: North Coast Ranges, n Sierra Nevada Foothills, Great Central Valley, Central Western California.