White-margined Sandmat (Sandmats (Euphorbia sect. Anisophyllum, previously Chamaesyce) of the Llano Estacado)

White-margined Sandmat

Euphorbia albomarginata

Description ²

Plants prostrate perennials; glabrous; plants rooting just proximal to the nodes; plants forming mats up to about 18 cm wide; rarely over 2 cm tall. Roots thick, dark-colored, and woody. Largest internodes around 1 mm in diameter. Stipules fused to form a scale, may be divided at the tip; entire to serrated. Leaves mostly orbicular, entire, and greatly unequal at the base, often having a reddish “splotch”. Cyathia large with yellowish to red glands (0.4-) 0.5-1.0 mm long. Appendages variable, from just a margin to longer than the gland is long, usually white. Cyathia generally visible without getting close to the plant. One of the showier species of the region. Plants are often covered with comparatively large cyathia.

Habitat and Distribution ²

Widespread throughout the Llano (Turner et. al., 2003; SRSC; Sibley Nature Center Herbarium) in various soils.

Comments ²

May be easily confused with E. serpens. The only completely accurate means of distinguishing the two is by counting the number of staminate flowers per cyathium: E. albomarginata has more than 10 staminate flowers, E. serpens has fewer than 10. However, there are some other characters that, when combined, can provide a reliable identification most of the time:

E. albomarginata: Perennial; main taproots thickened, rough, and woody; cyathia large with glands longer than 0.5 mm, usually visible to a person when standing.
E. serpens: Annual (or overwintering); main taproots thin and smooth (even when thickened from overwintering); cyathia small with glands shorter than 0.5 mm, usually not visible to a person when standing.

Sources and Credits

More Info

iNat Map

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