OregonFlora: Euphorbia lathyris vs. Euphorbia serpillifolia

	Euphorbia lathyris	Chamaesyce serpillifolia (synonym of Euphorbia serpillifolia)
	caper spurge, gopher plant, mole plant	thyme-leaved spurge, thymeleaf sandmat
Habit	Herbs or subshrubs biennial, 1.5–12 dm; stems erect, glabrous, glaucous.	Plants annual; stems prostrate to ascending, 5–40 cm, glabrous, sometimes glaucous; taprooted.
Leaves	opposite, narrowly oblong to ovate or subcordate, 30–150 × 5–30 mm, bases clasping; margins entire; tips acute; surfaces glabrous.	oblanceolate to oblong, 3–15 mm, occasionally with a central red spot; margins entire to shallowly toothed; tips rounded; surfaces glabrous; petioles 0.5–1.5 mm; stipules slender and entire to linear and dissected, 1–1.5 mm.
Inflorescences	involucres bell-shaped, 2.5–4 mm; glands 2-horned; horns rounded and short.	involucres 0.5–1 mm, glabrous; glands elliptic; gland appendages white.
Fruits	spherical, 5–15 mm.	spherical, 1–2 mm, glabrous.
Seeds	round, 4–6 mm, wrinkled or with shallow reticulate markings.	ovoid, 0.9–1.3 mm; smooth to wrinkled.

	Euphorbia lathyris	Chamaesyce serpillifolia
Distribution	[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.	Usually dry places but sometimes in wet areas, roadsides, disturbed areas. Flowering Jun–Sep. 0–1900 m. BR, BW, Casc, Col, ECas, Lava, Owy, Sisk, WV. CA, ID, NV, WA; southern Canada, most of US except southeast and parts of northeast, Mexico. Native. In California, some plants of this species have hairy stems, involucres, and fruits. These plants are accepted by some authorities as C. s. ssp. hirtula (ours, in turn, would be C. s. ssp. serpillifolia). Given the already small morphological differences between our species of Chamaesyce, we have chosen not to recognize the subspecies.
Source	Flora of Oregon, volume 2, page 645 Stephen Meyers	Flora of Oregon, volume 2, page 643 Stephen Meyers
Sibling taxa	E. crenulata, E. cyparissias, E. dentata, E. esula, E. helioscopia, E. myrsinites, E. oblongata, E. peplus, E. spathulata	C. glyptosperma, C. maculata, C. prostrata, C. serpens, C. serpillifolia
Synonyms		Chamaesyce serpillifolia ssp. serpillifolia, Euphorbia serpillifolia, Euphorbia serpillifolia ssp. serpillifolia
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: CA, OR, WA Local Web sites: CalFlora, CalPhotos, Flora NW, PNW Herbaria WildflowerSearch iNaturalist (observations) LBJ Wildflower Center SEINet Plants of the World Online Encyclopedia of Life Wikipedia Google Image Search

Chamaesyce serpillifolia

(synonym of Euphorbia serpillifolia)

caper spurge, gopher plant, mole plant

thyme-leaved spurge, thymeleaf sandmat

Habit

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

Plants annual; stems prostrate to ascending, 5–40 cm, glabrous, sometimes glaucous; taprooted.

Leaves

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

margins entire;

tips acute;

surfaces glabrous.

oblanceolate to oblong, 3–15 mm, occasionally with a central red spot;

margins entire to shallowly toothed;

tips rounded;

surfaces glabrous;

petioles 0.5–1.5 mm;

stipules slender and entire to linear and dissected, 1–1.5 mm.

Inflorescences

involucres bell-shaped, 2.5–4 mm;

glands 2-horned; horns rounded and short.

involucres 0.5–1 mm, glabrous;

glands elliptic;

gland appendages white.

Fruits

spherical, 5–15 mm.

spherical, 1–2 mm, glabrous.

Seeds

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

ovoid, 0.9–1.3 mm; smooth to wrinkled.

Chamaesyce serpillifolia

Distribution

[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.

Usually dry places but sometimes in wet areas, roadsides, disturbed areas. Flowering Jun–Sep. 0–1900 m. BR, BW, Casc, Col, ECas, Lava, Owy, Sisk, WV. CA, ID, NV, WA; southern Canada, most of US except southeast and parts of northeast, Mexico. Native.

In California, some plants of this species have hairy stems, involucres, and fruits. These plants are accepted by some authorities as C. s. ssp. hirtula (ours, in turn, would be C. s. ssp. serpillifolia). Given the already small morphological differences between our species of Chamaesyce, we have chosen not to recognize the subspecies.

Source

Flora of Oregon, volume 2, page 645
Stephen Meyers

Flora of Oregon, volume 2, page 643
Stephen Meyers

Sibling taxa