OregonFlora: Euphorbia prostrata vs. Euphorbia serpillifolia

	Euphorbia prostrata	Chamaesyce serpillifolia (synonym of Euphorbia serpillifolia)
		thyme-leaved spurge, thymeleaf sandmat
Habit		Plants annual; stems prostrate to ascending, 5–40 cm, glabrous, sometimes glaucous; taprooted.
Leaves		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 0.5–1 mm, glabrous; glands elliptic; gland appendages white.
Fruits		spherical, 1–2 mm, glabrous.
Seeds		ovoid, 0.9–1.3 mm; smooth to wrinkled.

	Euphorbia prostrata	Chamaesyce serpillifolia
Distribution	[WildflowerSearch map] [BONAP county map]
Discussion		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 643 Stephen Meyers
Sibling taxa	E. crenulata, E. cyparissias, E. dentata, E. esula, E. helioscopia, E. lathyris, 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: CA 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

Euphorbia prostrata

Chamaesyce serpillifolia

(synonym of Euphorbia serpillifolia)

thyme-leaved spurge, thymeleaf sandmat

Habit

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

Leaves

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 0.5–1 mm, glabrous;

glands elliptic;

gland appendages white.

Fruits

spherical, 1–2 mm, glabrous.

Seeds

ovoid, 0.9–1.3 mm; smooth to wrinkled.

Euphorbia prostrata

Chamaesyce serpillifolia

Distribution

[WildflowerSearch map]

[BONAP county map]

Discussion

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 643
Stephen Meyers

Sibling taxa