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.

ASTRAGALUS

Richard Spellenberg

Annual or perennial herb from crown, glabrous to hairy; hairs sometimes forked at base, branches parallel with leaf surface, sometimes very unequal
Stem 0 or prostrate to erect
Leaves odd-1-pinnate; leaflets generally jointed to midrib; stipules membranous, sometimes fused around stem at stem base
Inflorescence: raceme, axillary, sometimes head- or umbel-like; flowers 2–many
Flower bilateral; calyx 5-lobed; banner outside wings in bud, keel blades with small protrusion at base locking into pit on adjacent wing; 9 filaments fused, 1 free; ovary (and fruit) generally sessile, style slender, stigma minute
Fruit generally 1- or ± 2-chambered, often mottled, generally becoming ± dry; placenta on upper suture
Seeds 2–many, smooth, compressed, ± notched at attachment scar
Species in genus: > 2000 species: ± worldwide (380 in North America, 94 in CA including many rare taxa)
Etymology: (Greek: ankle-bone or dice, perhaps from rattling of seeds within fruit)
Reference: [Barneby 1964 Mem NY Bot Gard 20:1–1188; Isely 1986 Iowa State J Res 61:157–289]
Very difficult; both flower and fruit needed for identification; many good species appear similar; some species complexes need study. Taxa near province boundaries may appear in > 1 key. Varieties keyed under species for simplicity; species with vars. so identified in key. Fr length includes beak and any stalk-like base unless fruit body specified.

Native

A. pachypus Greene

Perennial, robust, rigid, bushy, sparsely leafy; hairs < 0.3 mm, appressed, ± scale-like, ± gray
Stem ± erect, 2–8 dm, wiry
Leaf 2.5–16.5 cm; leaflets 11–27, ± well separated, 3–34 mm, narrow
Inflorescence: flowers 4–28, well separated, ascending
Flower: petals white or cream, banner 15–22 mm, recurved ± 45°, keel 10.7–15.3 mm
Fruit ascending or spreading; body 12–28 mm, 4–8 mm wide, straight or ± curved, compressed side-to-side and stiffly leathery when mature, generally glabrous; stalk-like base 4–8 mm, stout; beak short, sharp, rigid, persistent; chambers 2
Ecology: Open slopes in grassland or scrub
Elevation: 500–1900 m.
Bioregional distribution: Tehachapi Mountain Area, s San Joaquin Valley, Inner South Coast Ranges, Western Transverse Ranges, Peninsular Ranges, w edge Desert.

Native

var. pachypus

Leaf: leaflets 11–21
Chromosomes: 2n=22
Ecology: Open areas or in scrub, often on gravelly clay, shale, or sandstone
Elevation: 500–1900 m.
Bioregional distribution: Tehachapi Mountain Area, s San Joaquin Valley, Inner South Coast Ranges, Western Transverse Ranges, w edge Desert
Flowering time: Mar–Jul
San Diego Co. plants have smaller flowers but are otherwise indistinguishable.