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.

PSOROTHAMNUS

Duane Isely

Perennial, shrub, small tree, generally with thorns, gland-dotted
Stem generally intricately branched
Leaves odd-1-pinnate or simple
Inflorescence: raceme, sometimes spike- or head-like, axillary or terminal; pedicels generally with bractlets
Flower: calyx lobes generally unequal, upper pair often largest; petals all arising from receptacle, violet, blue, or 2-colored (purple and white); stamens 10, filaments partly fused; ovules generally 2
Fruit indehiscent, included in or exserted from calyx, generally glandular
Seed 1
Species in genus: 9 species: sw US, Mex
Etymology: (Greek: scabshrub)
Reference: [Barneby 1977 Mem New York Bot Garden 27:21–54, 598–607]

Native

P. fremontii (A. Gray) Barneby

Shrub < 1 m, generally silvery-strigose
Leaf: leaflets 3–25 mm, linear to ovate, generally jointed to axis, except uppermost
Inflorescence: raceme, ± open; pedicels with bractlets
Flower: calyx 5–9 mm, lobes unequal, < tube; corolla 7–9.5 mm, violet-purple
Fruit exserted, 7–10 mm, glabrous; small glands forming longitudinal lines
Chromosomes: 2n=20
Ecology: Granite and volcanic slopes, flats, canyons
Elevation: 250–1350 m.
Bioregional distribution: e Desert Mountains, e Sonoran Desert
Distribution outside California: to s Utah, Arizona
Like P. arborescens except in fruit, geography
Horticultural information: TRY.