Euphorbia commutata |
Euphorbia aaron-rossii |
|
---|---|---|
tinted euphorbia, tinted woodland spurge |
Marble Canyon spurge, Ross' or Marble Canyon spurge |
|
Habit | Herbs, usually biennial, occasionally annual, with taproot. | Herbs, perennial, with deep stout rootstock. |
Stems | erect or ascending, decumbent and often branched near base, 10–40 cm, glabrous. |
erect, branched, densely clumped, previous year’s dead stems persistent, 25–45(–60) cm, glabrous, striate. |
Leaves | petiole usually 5–10 mm, 0–1 mm distally; blade usually oblanceolate to obovate, rarely ovate, 5–30 × 3–10 mm, base broadly attenuate, margins entire, apex usually obtuse to rounded, occasionally slightly retuse, surfaces glabrous; venation pinnate, midvein prominent. |
alternate, persisting, usually reflexed, occasionally spreading; stipules 0.1–0.3 mm; petiole 0.2–2.2 mm, glabrous; blade narrowly ovate to lanceolate proximally, narrowly lanceolate, linear, or filiform distally, 10–32 × 0.5–6.5 mm, base cuneate, margins entire, apex acute, surfaces pilose when young, sparsely strigose or glabrous with age; venation obscure, only midvein conspicuous. |
Involucre | campanulate, 1.7–2.5 × 1.5–2.5 mm, glabrous; glands 4, crescent-shaped; 0.6–1 × 0.8–1.5 mm; horns divergent, 0.5–1.1 mm. |
turbinate to campanulate, 2.2–3.7 × 1.5–2.5 mm, moderately strigose; glands 5, dark green, reniform, 0.7–1.1 × 1–1.6 mm; appendages white to pink, flabellate, 0.5–1.5 × 0.8–2.2 mm, dentate or erose. |
Staminate flowers | 9–15. |
20–25. |
Pistillate flowers | ovary glabrous; styles 0.9–1.3 mm, 2-fid. |
ovary strigose; styles 1–1.3 mm, 2-fid at apex. |
Capsules | ovoid-globose, 2.5–3.2 × 3 mm, slightly lobed; cocci rounded to ± flattened, smooth, glabrous; columella 1.5–2 mm. |
subglobose, 2–3 × 4 mm, sparsely strigose; columella 2–3 mm. |
Seeds | white to gray, broadly oblong-elliptic to ovoid or nearly globose, 1.5–2 × 1.3–1.6 mm, strongly small-pitted; caruncle irregularly winglike, conic, 0.6–1 × 0.7–0.9 mm. |
gray-green to gray-brown, globose-ovoid, 1.8–2.2 × 1.2–1.6 mm, longitudinally pitted; caruncle absent. |
Cyathial | arrangement: terminal pleiochasial branches (2–)3(–4), 1–3+ times 2-branched; pleiochasial bracts similar in shape and size to distal leaves; dichasial bracts distinct to basally subconnate, not imbricate, widely ovate, rhombic, or reniform, base cordate, rarely slightly perfoliate, margins entire, apex obtuse to rounded, mucronulate; axillary cymose branches 0–5. |
|
Cyathia | peduncle 0.5–1 mm. |
in terminal monochasia (thus appearing solitary at alternate nodes); peduncle 0.5–2.5 (or 10–25) mm, glabrous or sparsely strigose. |
Euphorbia commutata |
Euphorbia aaron-rossii |
|
Phenology | Flowering and fruiting spring–summer. | Flowering and fruiting spring–fall. |
Habitat | Bottomland and upland forests, bluffs and ledges, stream banks, glades, rarely fen margins. | Sandy soils and dunes, occasionally rocky slopes, riparian areas. |
Elevation | 50–1000 m. (200–3300 ft.) | 600–1300 m. (2000–4300 ft.) |
Distribution |
AL; AR; FL; GA; IA; IL; IN; KY; LA; MD; MI; MO; MS; NC; OH; OK; PA; SC; TN; VA; WI; WV; ON
|
AZ |
Discussion | Euphorbia aaron-rossii is restricted to the banks of the Colorado River in several small areas of the Grand and Marble canyons. The species is most closely related to E. strictior and E. wrightii, but due to its rarity, it has not been extensively studied. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
|
Source | FNA vol. 12, p. 300. | FNA vol. 12, p. 242. |
Parent taxa | Euphorbiaceae > Euphorbia > subg. Esula | Euphorbiaceae > Euphorbia > sect. Alectoroctonum |
Sibling taxa | ||
Synonyms | Galarhoeus austrinus, G. commutatus, Tithymalus commutatus | |
Name authority | Engelmann: in A. Gray, Manual ed. 2, 389. (1856) | A. H. Holmgren & N. H. Holmgren: Brittonia 40: 357, figs. 1, 2. (1988) |
Web links |