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Jepson Interchange (more information)
©Copyright 1993 by the Regents of the University of California

  • Up-to-date information about California vascular plants is available from the Jepson eFlora.



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.



Annual, perennial herb, monoecious or dioecious, generally glabrous; sap clear
Stems: central erect, branched; lateral < central, spreading to ascending
Leaves simple, cauline, opposite; stipules persistent; hairs simple
Staminate inflorescence spike-like, axillary; flowers clustered
Pistillate inflorescence: flowers clustered, axillary, below staminate flowers
Staminate flower: calyx 3-lobed; petals 0; stamens 8–15(20), free; nectary 0
Pistillate flower: sepals 3; petals 0; staminodes 2, elongated; ovary 2-chambered, bristly, styles free, simple
Fruit bristly
Seeds 1 per chamber, generally pitted; scar appendaged
Species in genus: 8 species: Eurasia, n Africa
Etymology: (Greek: Greek God Mercury)


M. annua L.

Annual, 1–3 dm, dioecious, ± glabrous
Leaf: stipules 1–1.5 mm, lanceolate-deltate; petiole 0.5–2(2.5) cm; blade 2–5 cm, ± ovate, margin serrate, ciliate
Staminate inflorescence < 2 cm, short-peduncled
Pistillate inflorescence: flowers 2–3; pedicel < 5 mm
Staminate flower: calyx ± 1 mm; stamens exserted
Pistillate flower: calyx ± 1 mm; ovary puberulent, styles ± 1 mm
Fruit 2–3 mm diam, finely bristly
Seeds 1.5–2 mm, shiny, pitted
Chromosomes: 2n=16, 32
Ecology: Open, disturbed areas, fields, roadsides
Elevation: < 200 m.
Bioregional distribution: San Francisco Bay Area
Distribution outside California: native to Europe

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