HIPPOCASTANACEAE

BUCKEYE FAMILY

William J. Stone

Shrub or tree
Leaves opposite, generally 4-ranked, palmately compound
Inflorescence: panicle or raceme, terminal; flowers many
Flowers showy, ± bilateral, some staminate; sepals 5, free or fused into tube, lobes unequal; petals 4–5, clawed, unequal; stamens 5–8, filaments long, slender; ovary chambers 3, ovules generally 2 per chamber
Fruit: capsule, spheric or slightly 3-lobed, leathery, roughly spiny to shiny
Seeds large, shiny
Genera in family: 3 genera, 18 species: n hemisphere
Reference: [Hardin 1957 Brittonia 9:145–170, 173–194]

AESCULUS

BUCKEYE, HORSE CHESTNUT

Shrub or tree, 4–30 m, < 15 m diam
Leaves deciduous
Inflorescence: pedicels jointed; seed-producing flowers generally at tip
Flower ill-smelling; sepals fused into tube; style of seed-producing flowers long, thick, of sterile flowers short
Species in genus: ± 15 species: n hemisphere; some cultivated
Etymology: (Latin: name of some oak)

Native

A. californica (Spach) Nutt.

CALIFORNIA BUCKEYE

Large shrub or tree, 4–12 m, broad, rounded
Leaf: leaflets 5–7, 6–17 cm, oblong-lanceolate, finely serrate, acute to acuminate; petiole 1–12 cm
Inflorescence panicle-like, erect, 1–2 dm, finely hairy; pedicel 3–10 mm
Flower: calyx 5–8 mm, 2-lobed; petals 12–18 mm, white to pale rose; stamens 5–7, 18–30 mm, exserted, anthers orange
Fruit generally 1 (sometimes 2–9), 5–8 cm diam, borne at inflorescence tip
Seed generally 1, 2–5 cm, glossy brown
Chromosomes: n=20
Ecology: Dry slopes, canyons, borders of streams
Elevation: < 1700 m.
Bioregional distribution: c&s Northwestern California, s Cascade Range, Sierra Nevada Foothills, Tehachapi Mountain Area, n&c Central Western California, sw Mojave Desert, scattered in Great Central Valley near foothills
Flowering time: May–Jun
All parts TOXIC. Native Americans used ground seed as fish poison; nectar and pollen toxic to honeybees
Horticultural information: 4, 5, 6, 7, 14, 15, 16, 17, 19, 20, 21, 22, 23, 24; IRR: 3, 8, 9, 10, 18; CVS. Generally deciduous Jun–Feb.