Euphorbia geyeri |
Euphorbia lathyris |
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Geyer's sandmat, Geyer's spurge |
caper spurge, euphorbe épurge, gopher plant, gopher spurge, mole plant |
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Habit | Herbs, annual, with taproot. | Herbs, annual or biennial, with taproot. | ||||
Stems | prostrate or slightly ascending, loosely mat-forming, 4–25(–45) cm, glabrous. |
erect, unbranched or branched, 200 cm, glabrous, glaucous. |
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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, decussate; petiole absent; blade linear to oblong-lanceolate, 30–120 × 3–25 mm, base acute, rounded, cordate or clasping, margins entire, apex acute or subobtuse, sometimes mucronate, surfaces glabrous, abaxial ± glaucous; venation pinnate, midvein prominent. |
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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. |
campanulate, 1.2–2.3 × 1.4–2.5 mm, glabrous; glands 4, elliptic, 0.3–0.6 × 1–1.3 mm; horns divergent, thick, tips rounded, dilated, 0.5–1.4 mm. |
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Staminate flowers | 5–20. |
25–30. |
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Pistillate flowers | ovary glabrous; styles 0.2–0.6 mm, 2-fid nearly 1/2 length. |
ovary glabrous; styles 0.7–2.2 mm, 2-fid. |
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Capsules | globose-ovoid, 1.5–2 × 1.5–3 mm, glabrous; columella 1.5–1.9 mm. |
depressed-globose, 9–12 × 12–16 mm, deeply 3-lobed, tardily dehiscent and appearing indehiscent, mesocarp spongy; cocci rounded, smooth, glabrous; columella 4–5.2 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. |
brownish or blackish, oblong, 4.5–6 × 3–4.2 mm, rugose, irregularly reticulate; caruncle substipitate, hat-shaped, 1.6–2 × 1.2–1.5 mm. |
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Cyathia | solitary or in small, cymose clusters at distal nodes; peduncle 1–2 mm. |
peduncle 0–0.5 mm. |
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Cyathial | arrangement: terminal pleiochasial branches 2–4, each 1–2 times 2-branched; pleiochasial bracts cordate-lanceolate, shorter and wider than distal leaves; dichasial bracts distinct, ovate-oblong to lanceolate, base subcordate, margins entire, apex acute; axillary cymose branches 0–10. |
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Euphorbia geyeri |
Euphorbia lathyris |
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Phenology | Flowering and fruiting winter–fall. | |||||
Habitat | Roadsides, cultivated fields, stream banks, waste places. | |||||
Elevation | 0–1800 m. (0–5900 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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AZ; CA; CT; ID; IL; MA; MD; MT; NC; OH; OR; PA; SC; TN; TX; VA; WA; WV; BC; ON; QC; Europe; Asia; Africa [Introduced in North America; introduced also in Mexico, South America, Australia]
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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.) |
Euphorbia lathyris is most likely native to the central and eastern Mediterranean region, but it is widely cultivated and often locally escaped in temperate regions worldwide, as in the flora area. (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. 304. | ||||
Parent taxa | Euphorbiaceae > Euphorbia > sect. Anisophyllum | Euphorbiaceae > Euphorbia > subg. Esula | ||||
Sibling taxa | ||||||
Subordinate taxa | ||||||
Synonyms | Chamaesyce geyeri | Galarhoeus lathyris, Tithymalus lathyris | ||||
Name authority | Engelmann: Boston J. Nat. Hist. 5: 260. (1845) | Linnaeus: Sp. Pl. 1: 457. (1753) — (as lathyrus) | ||||
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