OregonFlora: Euphorbia lathyris vs. Euphorbia myrsinites

	Euphorbia lathyris	Euphorbia myrsinites
	caper spurge, gopher plant, mole plant	myrtle spurge
Habit	Herbs or subshrubs biennial, 1.5–12 dm; stems erect, glabrous, glaucous.	Herbs perennial, 1–4 dm; stems decumbent to ascending, glabrous.
Leaves	opposite, narrowly oblong to ovate or subcordate, 30–150 × 5–30 mm, bases clasping; margins entire; tips acute; surfaces glabrous.	alternate (upper and floral leaves may be opposite or whorled), densely crowded on stem, obovate to obovate-oblong, 10–45 × 5–16 mm; margins entire to serrulate at least in upper 25%; tips mucronate; surfaces glabrous, glaucous;
Inflorescences	involucres bell-shaped, 2.5–4 mm; glands 2-horned; horns rounded and short.	involucres cone- to bell-shaped, 1.5–3 mm; glands shortly 2-horned.
Fruits	spherical, 5–15 mm.	round to oblong, 5–7mm.
Seeds	round, 4–6 mm, wrinkled or with shallow reticulate markings.	round to oblong, 3–4 mm; smooth or wrinkled.
±		sessile.

	Euphorbia lathyris	Euphorbia myrsinites
Distribution	[WildflowerSearch map] [BONAP county map]	[WildflowerSearch map] [BONAP county map]
Discussion	Disturbed areas. Flowering May–Jul. 0–500 m. Col, CR, Est, Sisk, WV. CA, ID, WA; scattered across North America; Asia, Europe. Exotic. Euphorbia lathyris is our only member of the genus to have only opposite leaves. It is sometimes planted in gardens based on the unsubstantiated belief it may deter moles and gophers.	Disturbed areas, escaped from nearby cultivation. Flowering Apr–Jun. 500–1000 m. BW, Col, Lava. CA, ID, WA; scattered in western US, MI, Ontario; Europe. Exotic. The densely crowded leaves on the stems and decumbent to ascending habit easily distinguish E. myrsinites from all other members of this genus in Oregon.
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. helioscopia, E. myrsinites, E. oblongata, E. peplus, E. spathulata	E. crenulata, E. cyparissias, E. dentata, E. esula, E. helioscopia, E. lathyris, 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	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 lathyris

Euphorbia myrsinites

caper spurge, gopher plant, mole plant

myrtle spurge

Habit

Herbs or subshrubs biennial, 1.5–12 dm; stems erect, glabrous, glaucous.

Herbs perennial, 1–4 dm; stems decumbent to ascending, glabrous.

Leaves

opposite, narrowly oblong to ovate or subcordate, 30–150 × 5–30 mm, bases clasping;

margins entire;

tips acute;

surfaces glabrous.

alternate (upper and floral leaves may be opposite or whorled), densely crowded on stem, obovate to obovate-oblong, 10–45 × 5–16 mm;

margins entire to serrulate at least in upper 25%;

tips mucronate;

surfaces glabrous, glaucous;

Inflorescences

involucres bell-shaped, 2.5–4 mm;

glands 2-horned; horns rounded and short.

involucres cone- to bell-shaped, 1.5–3 mm;

glands shortly 2-horned.

Fruits

spherical, 5–15 mm.

round to oblong, 5–7mm.

Seeds

round, 4–6 mm, wrinkled or with shallow reticulate markings.

round to oblong, 3–4 mm; smooth or wrinkled.

sessile.

Euphorbia lathyris

Euphorbia myrsinites

Distribution

[WildflowerSearch map]

[BONAP county map]

[WildflowerSearch map]

[BONAP county map]

Discussion

Disturbed areas. Flowering May–Jul. 0–500 m. Col, CR, Est, Sisk, WV. CA, ID, WA; scattered across North America; Asia, Europe. Exotic.

Euphorbia lathyris is our only member of the genus to have only opposite leaves. It is sometimes planted in gardens based on the unsubstantiated belief it may deter moles and gophers.

Disturbed areas, escaped from nearby cultivation. Flowering Apr–Jun. 500–1000 m. BW, Col, Lava. CA, ID, WA; scattered in western US, MI, Ontario; Europe. Exotic.

The densely crowded leaves on the stems and decumbent to ascending habit easily distinguish E. myrsinites from all other members of this genus in Oregon.

Source

Flora of Oregon, volume 2, page 645
Stephen Meyers

Sibling taxa