Euphorbia chamaesula |
Euphorbia meganaesos |
|
---|---|---|
mountain spurge |
|
|
Habit | Herbs, perennial, with thick rootstock. | Herbs, annual, with taproot. |
Stems | erect, branched, 40–90 cm, glabrous. |
prostrate to ascending, drooping at tips, 15–30 cm, glabrous. |
Leaves | petiole 0.5–1 mm; blade elliptic to oblong, 8–20(–40) × 3–6 mm, base truncate, rounded, or attenuate, margins entire, apex obtuse or acute, sometimes slightly mucronate, surfaces glabrous; venation inconspicuous, only midvein prominent. |
opposite; stipules distinct, divided nearly to base into linear-filiform segments, 1–2 mm, glabrous; petiole 0.5–1.3 mm, glabrous; blade narrowly oblong to oblong-obovate, often ± falcate, 5–16 × 1–4.5 mm, base subsymmetric to strongly oblique, margins sparsely spinulose-serrulate, apex rounded or broadly acute, abaxial surface pale grayish green, adaxial surface sometimes with reddish streak along midvein, both surfaces not papillate, glabrous; 3–5-veined at base. |
Involucre | turbinate or campanulate, 1.5–2.5 × 1.1–1.9 mm, glabrous; glands 4, crescent-shaped to semicircular, 0.5–0.8 × 1–1.8 mm; horns usually convergent, 0.2–0.8 mm. |
obconic, 0.7–0.9 × 0.4–0.6 mm, glabrous; glands 4, green to yellow-green, subequal, oblong, 0.1–0.2 × 0.2–0.3 mm; appendages white to reddish tinged, lunate to oblong, 0.1–0.3 × 0.3–0.5 mm (2 ± 2 times longer than other 2), entire or coarsely toothed. |
Staminate flowers | 8–12. |
2–5. |
Pistillate flowers | ovary glabrous; styles 1–1.8 mm, 2-fid. |
ovary glabrous; styles 0.2–0.3 mm, 2-fid at apex to nearly 1/2 length. |
Capsules | depressed-ovoid, 4.3–5 × 5–6 mm, 3-lobed; cocci rounded, smooth, glabrous; columella 3.5–4 mm. |
ovoid, cocci not elongated nor terminating in empty portion, 1.5 × 1.7 mm, glabrous; columella 1.3 mm. |
Seeds | gray to dark brown, ovoid-oblong, truncate at both ends, 2.6–3.4 × 2–2.6 mm, shallowly pitted to almost smooth; caruncle conic, 1 × 0.8 mm. |
reddish brown to brown, pyramidal to oblong-ovoid, weakly 4-angled in cross section, 0.9–1 × 0.7 mm, minutely beaded, with 3–4 broad, rounded, transverse ridges that do not interrupt abaxial keel. |
Cyathial | arrangement: terminal pleiochasial branches 3–5(–6), each 3–4 times 2-branched; pleiochasial bracts ovate-lanceolate to slightly subpandurate, similar in size or wider than distal leaves; dichasial bracts distinct, lanceolate to broadly ovate, base usually truncate to rounded or subcordate, sometimes attenuate, margins entire or slightly crenulate, apex usually obtuse to acute, occasionally acuminate; axillary cymose branches 2–8. |
|
Cyathia | peduncle 1–3 mm. |
solitary at distal nodes or on congested, axillary branches; peduncle 0.1–0.4 mm. |
2n | = 26. |
|
Euphorbia chamaesula |
Euphorbia meganaesos |
|
Phenology | Flowering and fruiting spring–summer. | Flowering and fruiting late spring–late summer. |
Habitat | Clearings in ponderosa pine forests, montane roadsides, dry streambeds, creek banks, sandy and gravelly soils. | Sandy beaches, edges of marshes, coastal prairies, roadsides. |
Elevation | 1700–2700 m. (5600–8900 ft.) | 0–10 m. (0–0 ft.) |
Distribution |
AZ; NM; Mexico (Chihuahua, Sonora)
|
LA; TX |
Discussion | Euphorbia chamaesula is easily distinguished from other perennial members of subg. Esula in western North America by its larger capsules and the vegetative shoots (without cyathia) that arise from the distal nodes of the stem proximal to the pleiochasia. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Euphorbia meganaesos is known only from coastal areas of southern Louisiana and adjacent Texas. This species was often considered conspecific with E. maculata in the past, but it differs from that species in being entirely glabrous. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 12, p. 300. | FNA vol. 12, p. 276. |
Parent taxa | Euphorbiaceae > Euphorbia > subg. Esula | Euphorbiaceae > Euphorbia > sect. Anisophyllum |
Sibling taxa | ||
Synonyms | Tithymalus chamaesula | |
Name authority | Boissier: Cent. Euphorb., 38. (1860) | Featherman: Rep. (Annual) Board Supervisors Louisiana State Seminary Learning Military Acad. 1870: 71, 105. (1871) |
Web links |