OregonFlora: Euphorbia helioscopia vs. Euphorbia esula

	Euphorbia helioscopia	Euphorbia esula
	mad woman's milk, wartweed	leafy spurge
Habit	Herbs annual, 1–5 dm; stems,erect, glabrous to sparsely hairy.	Herbs or subshrubs perennial, 3–7 dm; stems erect, glabrous and glaucous to sparsely pubescent.
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.	lower leaves alternate, narrowly oblong to narrowly oblanceolate, 30–90 × 3–8(10) mm; margins entire; tips obtuse to acuminate; surfaces glabrous, sessile or occasionally short-petiolate; floral leaves opposite or whorled, broadly ovate, 1–1.5 cm; margins entire to slightly crenate, sessile.
Inflorescences	involucres cone-shaped, 1–1.5 mm; glands not horned.	involucres bell-shaped, 2–3 mm; glands 2-horned.
Flowers	styles divided less than halfway to base.
Fruits	round, 2.5–3 mm.	oblong, 3–3.5 mm.
Seeds	ovoid, 1.5–2.5 mm, with reticulate pitting.	ellipsoid, 2–2.5 mm,
±		smooth.
2n		=16, 20, 48, 60, 64.

	Euphorbia helioscopia	Euphorbia esula
Distribution	[WildflowerSearch map] [BONAP county map]	[WildflowerSearch 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.	Roadsides, disturbed areas. Flowering May–Jul. 0–1400 m. BW, CR, ECas, Lava, Sisk. CA, ID, NV, WA; throughout US except TX and southeastern states, Mexico; Asia, Europe. Exotic.
Source	Flora of Oregon, volume 2, page 645 Stephen Meyers	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	E. crenulata, E. cyparissias, E. dentata, E. helioscopia, E. lathyris, E. myrsinites, E. oblongata, E. peplus, E. spathulata
Synonyms		Euphorbia virgata
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	Local floras: BC, OR Local Web sites: Flora NW, PNW Herbaria, Turner Photog. WildflowerSearch iNaturalist (observations) USDA Plants Database LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Euphorbia esula

mad woman's milk, wartweed

leafy spurge

Habit

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

Herbs or subshrubs perennial, 3–7 dm; stems erect, glabrous and glaucous to sparsely pubescent.

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.

lower leaves alternate, narrowly oblong to narrowly oblanceolate, 30–90 × 3–8(10) mm;

margins entire;

tips obtuse to acuminate;

surfaces glabrous, sessile or occasionally short-petiolate; floral leaves opposite or whorled, broadly ovate, 1–1.5 cm;

margins entire to slightly crenate, sessile.

Inflorescences

involucres cone-shaped, 1–1.5 mm;

glands not horned.

involucres bell-shaped, 2–3 mm;

glands 2-horned.

Flowers

styles divided less than halfway to base.

Fruits

round, 2.5–3 mm.

oblong, 3–3.5 mm.

Seeds

ovoid, 1.5–2.5 mm, with reticulate pitting.

ellipsoid, 2–2.5 mm,

smooth.

=16, 20, 48, 60, 64.

Euphorbia esula

Distribution

[WildflowerSearch map]

[BONAP county map]

[WildflowerSearch 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.

Roadsides, disturbed areas. Flowering May–Jul. 0–1400 m. BW, CR, ECas, Lava, Sisk. CA, ID, NV, WA; throughout US except TX and southeastern states, Mexico; Asia, Europe. Exotic.

Source

Flora of Oregon, volume 2, page 645
Stephen Meyers

Sibling taxa