Euphorbia geyeri |
Euphorbia vallis-mortae |
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Geyer's sandmat, Geyer's spurge |
Death Valley sandmat |
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Habit | Herbs, annual, with taproot. | Herbs, perennial, with thickened, woody taproot. | ||||
Stems | prostrate or slightly ascending, loosely mat-forming, 4–25(–45) cm, glabrous. |
prostrate to ascending, often mat-forming, 10–45 cm, pilose to villous. |
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Leaves | opposite; stipules usually distinct, occasionally connate basally on lower side, usually deeply parted into 3 or more filiform segments, 0.7–1.5 mm, glabrous; petiole 1–2 mm, glabrous; blade oblong to oblong-obovate or oblong-elliptic, 4–12 × 2–6 mm, base slightly asymmetric, angled or rounded, with one side usually expanded into small, rounded auricle, margins entire, apex usually truncate, occasionally emarginate, abaxial surface pale grayish green, both surfaces glabrous; only midvein conspicuous or venation obscurely pinnate (larger leaves). |
opposite; stipules distinct or connate, subulate to filiform, 0.4–1.1 mm, densely tomentose; petiole 0.4–1 mm, pilose to villous; blade suborbiculate to oblong-ovate, 3–8 × 2–6 mm, base slightly asymmetric, rounded, margins entire, apex rounded to obtuse, surfaces pilose to villous; 3-veined at base, midvein conspicuous, venation often obscured by pubescence. |
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Involucre | broadly campanulate, 1–1.5 × 0.7–0.9 mm, glabrous; glands 4, green to reddish, elliptic-oblong to nearly circular, slightly cupped to folded, 0.2–0.4 × 0.2–0.6 mm; appendages rudimentary to absent or white to reddish-tinged, usually rounded, sometimes pointed, (0–)0.5–1 × (0–)0.1–1.2 mm, distal margin entire or slightly toothed. |
obconic-campanulate, 1.2–2.3 × 1–1.8 mm, densely pilose to villous; glands 4, yellow to red, subcircular to oblong, 0.2–0.5 × 0.4–0.9 mm; appendages white, flabellate to oblong, 0.1–0.7 × 0.5–1.9 mm, distal margin entire or crenulate, adaxial surface ciliate-puberulent. |
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Staminate flowers | 5–20. |
15–22(–50). |
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Pistillate flowers | ovary glabrous; styles 0.2–0.6 mm, 2-fid nearly 1/2 length. |
ovary densely pilose; styles 0.4–0.8 mm, 2-fid 1/2 length. |
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Capsules | globose-ovoid, 1.5–2 × 1.5–3 mm, glabrous; columella 1.5–1.9 mm. |
ovoid, 1.5–2.2 × 1.8–2.2 mm, tomentose; columella 1.2–1.6 mm. |
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Seeds | ashy white, ovoid, terete to bluntly subangled in cross section, 1.1–1.7 × 0.9–1.2 mm, smooth, with smooth brown line from top to bottom on adaxial side. |
white, gray, or light brown, ovoid, sharply 4-angled in cross section, abaxial faces slightly convex, adaxial faces concave, 1.2–1.7 × 0.6–0.9 mm, smooth. |
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Cyathia | solitary or in small, cymose clusters at distal nodes; peduncle 1–2 mm. |
solitary at distal nodes; peduncle 0.5–1.8 mm. |
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Euphorbia geyeri |
Euphorbia vallis-mortae |
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Phenology | Flowering and fruiting late spring–fall. | |||||
Habitat | Roadsides, desert scrub, streamsides, sandy washes. | |||||
Elevation | 700–2000 m. (2300–6600 ft.) | |||||
Distribution |
CO; IA; IL; IN; KS; LA; MI; MN; MO; MS; MT; ND; NE; NM; OK; SD; TX; UT; WI; WY; MB; n Mexico
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CA |
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Discussion | Varieties 2 (2 in the flora). The two varieties of Euphorbia geyeri have been distinguished in large part by the presence of conspicuous involucral gland appendages in var. geyeri and the lack of appendages in var. wheeleriana. The two varieties are recognized here, but the variation in the size and presence of involucral gland appendages in the closely related E. bombensis suggests that this might be a somewhat variable character in this group of species. Euphorbia geyeri is widespread throughout the central United States in sandy soils. Populations at the eastern edge of the range are often considered adventive (for example, sandy soils along railroad grades in Michigan). Euphorbia geyeri resembles E. glyptosperma (both being entirely glabrous), but that species has serrulate leaves (near the apex) and strongly angled, transverse-ridged seeds whereas E. geyeri has entire leaves and smooth, rounded seeds. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
The specific epithet of Euphorbia vallis-mortae is a misnomer because the species does not occur in Death Valley; instead, it is found at the transition of the northern edge of the Mojave Desert and the foothills of the southern Sierra Nevada in Inyo, Kern, and San Bernardino counties. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
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Key |
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Source | FNA vol. 12, p. 268. | FNA vol. 12, p. 291. | ||||
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > sect. Anisophyllum | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Chamaesyce geyeri | Chamaesyce vallis-mortae | ||||
Name authority | Engelmann: Boston J. Nat. Hist. 5: 260. (1845) | (Millspaugh) J. T. Howell: Madroño 2: 19. (1931) | ||||
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