Duration: Perennial

Nativity: Native

Lifeform: Forb/Herb

General: Perennial herbs, 10-25 cm tall, from moderately thickened, slightly woody rootstock; stems ascending to erect, sometimes prostrate; herbage strigose, short-sericeous, or villous. 

Leaves: Opposite and sessile or subsessile along the stems; blade ovate-deltate or falcate (sickle-shaped), 4-12 mm long and 3-7 mm wide, with an asymmetric base and entire, revolute (rolled under) margins; lower surface with a prominent midvein, and both the upper and lower surfaces covered with hairs; stipules distinct, filiform, 1 mm long.

Flowers: Has the highly modified flower structure characteristic of Euphorbias. Structures called cyathia appear to be individual flowers, but are composed of fused-together bracts forming a cup (involucre), with peripheral nectary glands which are often subtended by petal-like bracts called petaloid appendages. Within the cup there is a ring of inconspicuous male flowers, each reduced to a single stamen. Out of the middle protrudes a single, stalked female flower which lacks petals. In E. lata, the cyathia (flower structures) are solitary in leaf axils near branch tips; Involucres are broadly bell-shaped, 2 mm high, and strigose (with stiff sharp appressed hairs) with 4 greenish oblong glands around the edge; petaloid appendages white, joined into a narrow band (sometimes rudamentary); 25-35 staminate flowers.

Fruits: Capsules ovoid, 2 mm high, 3-celled, strigose to short-sericeous or villous; containing 3 whitish oblong seeds, 1.5 mm long, four-angled in cross section, smooth with concave faces.

Ecology: Found on mountain slopes, in canyons, basins, rocky prairies, roadsides, and disturbed sites; usually in calcareous soils but sometimes in igneous-derived, sandy or rocky soils, from 2,000-7,500 ft (610-2286 m); flowers April-September.

Distribution: CO, KS, NM, OK, and TX; south to nw MEX

Notes: This species belongs to the Chamaesyce subgenus of Euphorbia. Some treatments, even recent ones, continue to treat Chamaesyce as a separate genus even though molecular evidence places it within Euphorbia. Chamaesyce spp are distinct based on their leaves which are always opposite and and often have asymmetric bases; cyathia (flower structures) in leaf axils, not at branch tips, and usually with petaloid appendages; and stipules present and not gland-like. E. lata is distinguished as a low-growing (but usually not prostrate and mat-forming) perennial with an olive-drab or light purplish cast; narrow leaves which are often sickle-shaped, with edges that curl under, and hairs on both the upper and lower surfaces; and hairy seed pods. It is wise to make a collection whenever ID to species is needed, as Chamaesyces are difficult to identify in the field, and multiple species of the genus will commonly grow side-by-side.

Ethnobotany: Unknown

Etymology: Euphorbia is named for Euphorbus, Greek physician of Juba II, King of Mauretania; lata comes from the Latin latus, broad or wide.

Editor: AHazelton 2017