OregonFlora: Euphorbia helioscopia

	Euphorbia helioscopia
	mad woman's milk, wartweed
Habit	Herbs annual, 1–5 dm; stems,erect, glabrous to sparsely hairy.
Leaves	alternate (upper leaves may be opposite), obovate to spatulate, 10–30 × 5–15 mm; margins toothed in at least upper 25%; entire below; tips rounded; surfaces glabrous, sessile.
Inflorescences	involucres cone-shaped, 1–1.5 mm; glands not horned.
Flowers	styles divided less than halfway to base.
Fruits	round, 2.5–3 mm.
Seeds	ovoid, 1.5–2.5 mm, with reticulate pitting.

	Euphorbia helioscopia
Distribution	[WildflowerSearch map] [BONAP county map]
Discussion	Disturbed areas. Flowering Apr–Jul. 0–200 m. CR, WV. CA, WA; scattered throughout North America; Asia, Europe. Exotic. Euphorbia helioscopia is easily confused with E. spathulata. The former is an exotic species introduced from Eurasia, while E. spathulata is considered native. The most reliable characteristic separating these taxa is the size of the involucres.
Source	Flora of Oregon, volume 2, page 645 Stephen Meyers
Sibling taxa	E. crenulata, E. cyparissias, E. dentata, E. esula, E. lathyris, E. myrsinites, E. oblongata, E. peplus, E. spathulata
Web links	Local floras: BC, CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Euphorbia helioscopia

mad woman's milk, wartweed

Habit

Herbs annual, 1–5 dm; stems,erect, glabrous to sparsely hairy.

Leaves

alternate (upper leaves may be opposite), obovate to spatulate, 10–30 × 5–15 mm;

margins toothed in at least upper 25%; entire below;

tips rounded;

surfaces glabrous, sessile.

Inflorescences

involucres cone-shaped, 1–1.5 mm;

glands not horned.

Flowers

styles divided less than halfway to base.

Fruits

round, 2.5–3 mm.

Seeds

ovoid, 1.5–2.5 mm, with reticulate pitting.

Euphorbia helioscopia

Distribution

[WildflowerSearch map]

[BONAP county map]

Discussion

Disturbed areas. Flowering Apr–Jul. 0–200 m. CR, WV. CA, WA; scattered throughout North America; Asia, Europe. Exotic.

Euphorbia helioscopia is easily confused with E. spathulata. The former is an exotic species introduced from Eurasia, while E. spathulata is considered native. The most reliable characteristic separating these taxa is the size of the involucres.

Source

Flora of Oregon, volume 2, page 645
Stephen Meyers

Sibling taxa