Euphorbia cordifolia |
Euphorbia mercurialina |
|
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heartleaf sandmat |
Mercury spurge |
|
Habit | Herbs, annual, with taproot. | Herbs, perennial, with thickened, spreading rootstock. |
Stems | prostrate, occasionally mat-forming, 10–43 cm, glabrous. |
erect, unbranched or branched, solitary or few, previous year's dead stems not persistent, 20–33 cm, glabrous or villous to lanate. |
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. |
alternate; stipules 0.1–0.2 mm; petiole (1–)2.5–5(–6) mm, ciliate to lanate; blade elliptic to ovate-deltate, proximal greatly reduced, scalelike, 34–55 × 20–26 mm, base rounded or cuneate, margins entire, densely ciliate, apex rounded to acute, abaxial surface sparsely pilose to villous (to lanate on midrib), adaxial surface glabrous; venation obscure, only midvein conspicuous. |
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. |
campanulate or hemispheric, 1.5–2.5 × 2–3 mm, glabrous; glands 5, green, elliptic-reniform, 0.5 × 2 mm; appendages white, narrowly transversely-oblong to lunate, 0.6 × 2.5 mm, slightly erose. |
Staminate flowers | 5–40. |
10–15. |
Pistillate flowers | ovary glabrous; styles 0.5–0.8 mm, 2-fid nearly entire length. |
ovary glabrous; styles 0.7–1.5 mm, 2-fid at apex. |
Capsules | ovoid, 2–3 mm diam., glabrous; columella 1.2–2.7 mm. |
depressed-globose, 2.3–3.3 × 4.4–5 mm, glabrous; columella 2.7–3 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. |
tan to dark brown, ovoid, 2.2 × 1.6 mm, with shallow and coarse depressions; caruncle absent. |
Cyathia | solitary at distal nodes; peduncle 0.9–3 mm. |
usually in terminal pleiochasia, rarely dichasia; peduncle 1.3–2.7 mm (to 40–70 mm for central cyathium), filiform, glabrous. |
Euphorbia cordifolia |
Euphorbia mercurialina |
|
Phenology | Flowering and fruiting summer–fall. | Flowering and fruiting spring. |
Habitat | Xeric oak-pine scrub, pine-barrens, sand barrens, sandy stream banks. | Dry to mesic wooded slopes and ravines. |
Elevation | 0–200 m. (0–700 ft.) | 100–600 m. (300–2000 ft.) |
Distribution |
AL; AR; FL; GA; LA; MS; NC; OK; SC; TX
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AL; GA; KY; NC; TN
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Discussion | Euphorbia cordifolia is easily identified by its cordate to rounded leaf base and distinctive filiform stipules. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia mercurialina is restricted primarily to the Cumberland Plateau and southern Appalachians, with disjunct occurrences in south-central North Carolina in the lower Piedmont. The North Carolina plants are markedly hairier than plants elsewhere, with villous or lanate stems, petioles, and abaxial leaf midribs. Euphorbia mercurialina has been reported from Florida and Virginia in the past. The Virginia plants were apparently planted (A. S. Weakley 2010), and the Florida reports are most certainly in error. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 265. | FNA vol. 12, p. 249. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Alectoroctonum |
Sibling taxa | ||
Synonyms | Chamaesyce cordifolia | Tithymalopsis mercurialina |
Name authority | Elliott: Sketch. Bot. S. Carolina 2: 656. (1824) | Michaux: Fl. Bor.-Amer. 2: 212. (1803) |
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