35. Euphorbia cordifolia Elliott, Sketch. Bot. S. Carolina. 2: 656. 1824.
Heartleaf sandmat Heartleaf sandmat
Chamaesyce cordifolia (Elliott) Small
Herbs, annual, with taproot. Stems prostrate, occasionally mat-forming, 10–43 cm, glabrous. Leaves opposite; stipules usually distinct, occasionally connate at base, filiform, 1–1.2(–2.8) mm, usually glabrous, rarely pilose; petiole 0.4–1 mm, usually glabrous; blade ovate to oblong, 4.4–12 × 2.6–7.6 mm, base asymmetric, cordate to rounded, margins entire, apex rounded to mucronulate, surfaces glabrous; only midvein conspicuous. Cyathia solitary at distal nodes; peduncle 0.9–3 mm. Involucre campanulate, 1–1.3 × 1–1.3 mm, glabrous; glands 4, yellowish to pink, elliptic, 0.3–0.5 × 0.5–1 mm; appendages whitish to pink, sometimes drying red, elliptic to ovoid, 1.1–1.5 × 1.2–1.9 mm, distal margin entire, retuse, or erose. Staminate flowers 5–40. Pistillate flowers: ovary glabrous; styles 0.5–0.8 mm, 2-fid nearly entire length. Capsules ovoid, 2–3 mm diam., glabrous; columella 1.2–2.7 mm. Seeds gray or tan with dark brown mottling, ovoid, bluntly 3–4-angled in cross section, 1.8–2.1 × 1.2–1.4 mm, smooth to rugose.
Flowering and fruiting summer–fall. Xeric oak-pine scrub, pine-barrens, sand barrens, sandy stream banks; 0–200 m; Ala., Ark., Fla., Ga., La., Miss., N.C., Okla., S.C., Tex.
Euphorbia cordifolia is easily identified by its cordate to rounded leaf base and distinctive filiform stipules.