RHAMNACEAE

BUCKTHORN FAMILY

John O. Sawyer, Jr. (except Ceanothus)

Shrub, vine, tree, generally erect, often thorny
Leaves simple, generally alternate, often clustered on short-shoots, generally petioled, generally stipuled; blade often 1–3-ribbed from base
Inflorescence: cyme, panicle, or flowers solitary in axils
Flower generally bisexual, radial; hypanthium subtending, surrounding, or partly fused to ovary; sepals 4 or 5; petals 0, 4, or 5, clawed; stamens 4 or 5, alternate sepals, attached to hypanthium top, each generally fitting into a petal concavity; ovary superior or partly inferior, chambers 2–5, each 1–2-ovuled, style lobes or parts 1–3
Fruit: capsule, drupe
Genera in family: 55 genera, 900 species: especially tropical, subtropical; some cultivated (Ceanothus ; Colletia , anchor-plant; Gouania ; Phylica ; Rhamnus ; Ventilago ; Ziziphus )
Reference: [Brizicky 1965 J Arnold Arbor 45:439–463]

ADOLPHIA

Shrub
Stem: branches opposite, rigid, green; twigs spreading, jointed at base, thorn-tipped
Leaves opposite, sometimes clustered in axils, early deciduous; stipules ± triangular, black, shiny; blade entire, 1–3-ribbed from base
Inflorescence: small axillary clusters
Flower: hypanthium bowl-shaped, 10-ribbed, free from ovary, in fruit papery, not splitting; sepals 5, triangular, persistent; petals 5, spoon-shaped, white; stamens 5; ovary superior, chambers 3, each 1-ovuled, style parts 3
Fruit: capsule, spheric
Species in genus: 2 species: SCo, PR, TX, Mex
Etymology: (Adolphe Brongniart, student of Rhamnaceae, 1801–1876)

Native

A. californica S. Watson

SPINESHRUB, CALIFORNIA ADOLPHIA

Shrub < 1 m
Stem: twigs stout, glabrous to puberulent
Leaf: petiole 2–4 mm; blade 3–9 mm, oblong, base wedge-shaped, tip obtuse to acute
Flower: hypanthium 3 mm wide, 2 mm deep; petals 2 mm
Fruit 5 mm
Ecology: Coastal scrub, chaparral
Elevation: < 300 m.
Bioregional distribution: South Coast, Peninsular Ranges
Distribution outside California: Mexico
Local.