Euphorbia platysperma
Flat-seeded spurge, Flat-Seeded Spurge
Family: Euphorbiaceae · Type: Herb · Native
Conservation status: CNPS 1B.2
Euphorbia platysperma (Flat-seeded spurge) is a native California herb in the Euphorbiaceae family, recognized by large flattened seeds diagnostic.
Flat-seeded spurge is a rare (CNPS 1B.2) California native annual found in the Coachella Valley in sandy soil at elevations below 100 meters. Flowering in May, this plant produces small flowers in distinctive cyathia with four transversely obovate glands. Growing with prostrate, repeatedly forking stems that are distinctively two-faced, it spreads close to the ground in delicate patterns. Its opposite leaves are short-petioled, 5 to 10 millimeters long, with oblong to obovate blades that have rounded or tapered bases and obtuse tips. The fruit is widely ovoid and less than 4.5 millimeters long, producing smooth white seeds that are slightly two-angled and flattened.
Identification and appearance
Key characters: 18 sympatric species; large flattened seeds diagnostic
Habitat and range
Habitat: Sandy soil
Elevation: < 100 m
Outside California: to southwestern Arizona, northern Sonora
Bloom period
Euphorbia platysperma blooms May.
Conservation status
CNPS 1B.2
How to tell it apart
vs Croton: Euphorbia bleeds milky white latex and packs its flowers into a tiny cup (cyathium) rimmed with nectar glands; Croton has watery sap, stellate or scaly hairs, and ordinary small separate male and female flowers.; vs Stillingia: Euphorbia flowers sit in a gland-bearing cyathium; Stillingia bears its flowers in a spike with a pair of glands flanking each subtending bract and has no cyathium cup.; vs Ditaxis: Euphorbia has latex and the cyathium; Ditaxis has clear sap, 5-parted petaled male and female flowers, and 2-forked (malpighiaceous) hairs.; vs Asclepias: Both ooze milky sap, but Euphorbia's minute flowers cluster in a cyathium and ripen into a 3-lobed capsule; milkweeds have showy 5-parted flowers with a crown and paired follicles of plumed seeds.; vs Polygonum: Prostrate mat spurges leak milky sap when torn and have paired stipules with opposite leaves at the nodes; knotweeds have clear sap and a papery sheath (ocrea) wrapping each node.
Frequently asked questions
Is Euphorbia platysperma native to California?
Yes. Euphorbia platysperma is native to California (recorded as native).
When does Euphorbia platysperma bloom?
Euphorbia platysperma blooms May.
What plant family does Euphorbia platysperma belong to?
Euphorbia platysperma is in the Euphorbiaceae family, genus Euphorbia.
Is Euphorbia platysperma rare or endangered?
Euphorbia platysperma carries California Rare Plant Rank 1B.2, state rank S1.
What habitat does Euphorbia platysperma grow in?
Euphorbia platysperma grows in Sandy soil.
Related species
Other California species in the same genus, family, or bioregion.
Sources: Jepson eFlora · CalPhotos · CDFW CNDDB
Last updated 2026-10-07
Data from The California Species Project — 14,000+ California species with verified data from CNPS, CDFW, USFWS, Cal-IPC, and more.