Euphorbia polycarpa |
Euphorbia carunculata |
|
---|---|---|
smallseed sandmat |
sand-dune sandmat or spurge |
|
Habit | Herbs, annual, with taproot. | |
Stems | prostrate, spreading and lanky or occasionally mat-forming, ± succulent, 70–150 cm, glabrous. |
|
Leaves | opposite; stipules usually distinct, occasionally connate basally (primarily at distal nodes), usually divided into 2–5 subulate to subulate-filiform segments, occasionally forming narrow deltate segments (primarily at distal nodes), 0.8–1.8 mm, glabrous; petiole 3.1–6.3 mm, glabrous; blade ovate to elliptic-oblong, 5–26 × 4–12 mm, base subsymmetric to symmetric, rounded to cuneate, margins entire, apex usually mucronate, rarely acute or obtuse, surfaces glabrous; pinnately veined. |
|
Involucre | campanulate, 1.1–1.8 × 1.5–2.5 mm, glabrous; glands 4, yellowish, sessile or short stipitate, circular to oblong, 0.5–0.7 × 0.5–0.8 mm; appendages white to yellowish, ovate to oblong, occasionally rudimentary, (0–)0.8–1.2 × 0.8–1.5 mm, distal margin entire. |
|
Staminate flowers | 15–25. |
|
Pistillate flowers | ovary glabrous; styles 0.7–1 mm, 2-fid 1/2 length. |
|
Capsules | ovoid, 4.7–5.5(–6) × 3.6–5.1 mm, glabrous; columella 4.3–5.1 mm. |
|
Seeds | grayish white to reddish brown mottled, bottle-shaped, strongly dorsiventrally compressed and weakly 3-angled in cross section, (2.8–)4.1–5.2 × 1.2–2(–3.4) mm, smooth; carunclelike structure linear, 0.4–0.5 × 0.1–0.2 mm. |
|
Euphorbia | polycarpa is a highly variable species distributed throughout the Baja California peninsula, eastern Sonora, and the arid southwestern United States from southwestern Arizona to southern Nevada and central California. |
|
l | . |
|
c | . |
|
Wheeler | (1941) divided the species into seven varieties, the majority of which occur in Baja California Sur. |
|
He | reported two of these for the United States: var. hirtella and var. polycarpa. |
|
Variety | hirtella, as the name suggests, was applied to hairy plants. |
|
However | , it is here treated as a synonym of var. polycarpa, because variation in pubescence shows no geographic segregation and ranges along a continuum from glabrous or sparsely to densely hairy, and because glabrous and hairy branches can occur on the same individual. |
|
Cyathia | solitary at distal nodes; peduncle 1.4–3.6 mm. |
|
Euphorbia polycarpa |
Euphorbia carunculata |
|
Phenology | Flowering and fruiting summer–fall. | |
Habitat | Sand dunes. | |
Elevation | 400–1300 m. (1300–4300 ft.) | |
Distribution |
AZ; CA; NV; nw Mexico
|
KS; NM; OK; TX; Mexico (Chihuahua) |
Discussion | Varieties 5 (1 in the flora). Some of the varieties occurring in Mexico are highly divergent and appear to be sufficiently distinct to merit recognition as species. However, within the flora area, Euphorbia polycarpa is relatively uniform, and the only noteworthy variation involves the size of the involucral gland appendages. In the portion of the California Floristic Province occupied by E. polycarpa (Los Angeles, Orange, western Riverside, western San Diego, and Ventura counties) the appendages are conspicuously larger than those of plants throughout the remainder of its range in the southwestern United States (0.4–1.2 versus 0.1–0.3 mm). Large-appendaged plants are also common in Baja California and correspond well with the type collection. The taxonomic significance of this variation is not clear at this time, and the small-appendaged plants may merit segregation as an infraspecific taxon. However, no formal changes are proposed, awaiting a comprehensive review of the species throughout its range. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia carunculata has a highly localized and scattered distribution. The species is restricted to sand dunes and known from only a handful of localities throughout its relatively wide range. The seeds are unique in being bottle-shaped and strongly laterally compressed, and unlike other members of sect. Anisophyllum, there is a minute, linear, carunclelike protuberance at the hilum. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 283. | FNA vol. 12, p. 262. |
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Subordinate taxa | ||
Synonyms | Chamaesyce polycarpa | Chamaesyce carunculata |
Name authority | Bentham: Bot. Voy. Sulphur, 50. (1844) | Waterfall: Rhodora 50: 63. (1948) |
Web links |