EUPHORBIACEAE

SPURGE FAMILY

Grady L. Webster, except as specified

Annual, perennial herb, shrub, tree, vine, monoecious or dioecious
Stem generally branched, sometimes fleshy or spiny
Leaves generally simple, alternate or opposite, generally stipuled, petioled; blade entire, toothed, or palmately lobed
Inflorescence: cyme, panicle, raceme, spike; flowers sometimes in clusters (dense, enclosed by involucre, flower-like in Chamaesyce, Euphorbia ), terminal or axillary
Flower unisexual, ± radial; sepals generally 3–5, free or fused; petals generally 0; stamens 1–many, free or filaments fused; ovary superior, chambers 1–4, styles free or fused, simple or lobed
Fruit: generally capsule
Seeds 1–2 per chamber; seed scar appendage sometimes present, pad- to dome-like
Genera in family: 300 genera, 7500 species: ± worldwide especially tropical; some cultivated (Aleurites , tung oil; Euphorbia subsp.; Hevea , rubber; Ricinus )
Reference: [Webster 1967 J Arnold Arbor 48:303–430]
Many species ± highly TOXIC.

EUPHORBIA

SPURGE

Daryl L. Koutnik

Annual, perennial herb, generally monoecious, glabrous or hairy
Stem ascending to erect, < 1 m; branches forked, forks equal
Leaves cauline, generally alternate; stipules 0 or gland-like; petiole present or 0; leaf base symmetrical
Inflorescence flower-like or not, generally clustered; clusters generally umbel-like or cyme-like; involucre ± bell-shaped; bracts 5, fused; glands generally 4, distal appendages generally 0; flowers central
Staminate flowers 5–many, generally in 5 clusters around pistillate flower
Pistillate flower 1, central, stalked; ovary chambers 3, ovule 1 per chamber, styles 3, separate or fused at base, divided or entire
Fruit: capsule, round to 3-angled or -lobed in X -section
Seed round or angled in X -section; surface smooth or sculptured, generally with a knob-like structure at attachment scar
Species in genus: ± 1500 species: warm temp to tropical, worldwide. See Chamaesyce
Etymology: (Latin: Euphorbus, Physician to the King of Mauritania, 1st century)
Reference: [Wheeler 1936 Bull S Calif Acad Sci 35:127–147]
Horticultural information: STBL.

Native

E. palmeri S. Watson

Perennial
Stem ascending to erect, 1–3.5 dm, glabrous
Leaf 0.5–2 cm, petioled to sessile; blade obovate to ovate, glabrous, tip obtuse to rounded, margin entire
Inflorescence: involucre < 3 mm, obconic, glabrous; gland < 1.5 mm, oblong, margin entire to scalloped, shortly 2-horned
Staminate flowers < 20
Pistillate flower: style divided < 1/2 length
Fruit ± 4 mm, ovoid, round, glabrous
Seed ± 2.5 mm, oblong, round, gray; surface net-like
Ecology: Common. Dry slopes, flats
Elevation: 1300–2800 m.
Bioregional distribution: Southwestern California
Distribution outside California: to Utah, Arizona
Intergrades with E. incisa , especially in deserts.