Asclepias obovata |
Asclepias nyctaginifolia |
|
---|---|---|
pineland milkweed |
Mohave milkweed, Mojave milkweed |
|
Habit | Herbs. | Herbs. |
Stems | 1 (rarely more), erect to spreading, unbranched, 40–70(–200) cm, densely hirtellous to velutinous, not glaucous, rhizomes absent. |
1–10, spreading or decumbent to erect, unbranched or rarely branched near base, 15–40 cm, puberulent with curved trichomes or hirtellous, not glaucous, rhizomatous. |
Leaves | opposite, petiolate, with 1 or 2 stipular colleters on each side of petiole; petiole 1–4 mm, densely hirtellous to velutinous; blade oblong or elliptic to obovate or ovate, 4–9 × 1–3.5 cm, subcoriaceous, base rounded or truncate to cordate, margins sometimes crisped, apex acute to truncate, sometimes emarginate, often mucronate, venation brochidodromous, surfaces densely hirtellous to velutinous abaxially, hirtellous adaxially, margins ciliate, 8–12 laminar colleters. |
persistent or gradually caducous from base, opposite, petiolate, with 1 or 2 stipular colleters on each side of petiole plus 0–4 in axil; petiole 6–25 mm, puberulent with curved trichomes to hirtellous; blade ovate to lanceolate, 4.5–15 × 1.5–7.5 cm, chartaceous, base cuneate or obtuse to truncate or subcordate, margins sometimes crisped, apex obtuse to acute, venation eucamptodromous to faintly brochidodromous, surfaces hirtellous, rarely conduplicate, 0–12 laminar colleters. |
Inflorescences | extra-axillary, sometimes also appearing terminal, sessile or pedunculate, 7–31-flowered; peduncle 0–0.5 cm, densely hirtellous to velutinous, with 1 caducous bract at the base of each pedicel. |
extra-axillary, sessile or pedunculate, 5–28-flowered; peduncle 0–1 cm, hirtellous, with 1 caducous bract at the base of each pedicel. |
Pedicels | 10–12 mm, densely hirtellous to velutinous. |
17–30 mm, hirtellous. |
Flowers | erect to pendent; calyx lobes elliptic, 5–6 mm, apex acute, densely hirtellous; corolla green, sometimes tinged reddish or bronze, lobes reflexed, sometimes with spreading tips, elliptic, 7–9 mm, apex acute, glabrous abaxially, minutely papillose at base adaxially; gynostegial column 1–1.5 mm; fused anthers green, obconic, 2.5–4 mm, wings right-triangular, open at base, apical appendages broadly ovate; corona segments bronze to yellow, often tinged red, sometimes apically cream or pale, stipitate, tubular, somewhat flattened laterally, flared at base, 5–8 mm, greatly exceeding style apex, apex rounded, flared, glabrous, internal appendage falcate, exserted, sharply incurved over style apex, glabrous; style apex shallowly depressed, green. |
erect; calyx lobes lanceolate, 3–5 mm, apex acute, hirtellous; corolla green, sometimes tinged reddish or purplish abaxially, lobes reflexed, elliptic to lanceolate, 9–13 mm, apex acute, minutely hirtellous throughout or glabrous at tips abaxially, glabrous adaxially; gynostegial column 0.3–0.5 mm; fused anthers brown, obconic, 1.7–2 mm, wings triangular, widest at middle, closed, apical appendages ovate; corona segments cream to green with cream apex, fading yellow, sessile, tubular, slightly sinuous, relatively stout, 8–11 mm, greatly exceeding style apex, apex slightly flared, truncate, minutely papillose to glabrate, internal appendage lingulate, sharply incurved, barely exserted, greatly exceeded by segment margin and exposing cavity, minutely papillose. |
Seeds | broadly ovate, 8–9 × 6–7 mm, margin winged, faces smooth; coma 2–5 cm. |
ovate to oval, 6–8 × 4.5–6.5 mm, margin winged, faces smooth; coma 2–4 cm. |
Follicles | erect on upcurved pedicels, narrowly to broadly fusiform, 7.5–12.5 × 1.5–2.5 cm, apex acuminate, smooth, densely hirtellous to velutinous. |
erect on upcurved pedicels, lance-ovoid, 6.5–10 × 1.5–3 cm, apex acuminate, smooth, sometimes faintly striate, puberulent with curved trichomes or hirtellous. |
Asclepias obovata |
Asclepias nyctaginifolia |
|
Phenology | Flowering May–Sep; fruiting Jul–Oct. | Flowering Apr–Sep(–Nov); fruiting May–Nov. |
Habitat | Hills, slopes, flats, ridges, sandhills, ditches, seeps, bogs, sandstone, sandy, rocky, silty, and clay soils, pine flatwoods, pine savannas, pine, pine-oak, and bottomland hardwood forests, prairies, often following fires. | Arroyos, canyons, mesas, hills, slopes, bajadas, ridges, plains, valleys, limestone, sandstone, granite, andesite, rhyolite, volcanic ash, sandy, silty, and gravel soils, desert scrub, mesquite and oak grasslands, oak and oak-juniper, and pinyon-juniper woodlands, chaparral, pine-oak forests. |
Elevation | 0–200 m. (0–700 ft.) | 300–1800(–2000) m. (1000–5900(–6600) ft.) |
Distribution |
AL; AR; FL; GA; LA; MS; OK; SC; TX
|
AZ; CA; NM; NV; Mexico (Sonora)
|
Discussion | Asclepias obovata is a common milkweed of seasonally wet, sandy soils in pine woodlands of the Gulf Coastal Plain and (rarely) the southern Atlantic Coastal Plain. It is rare and considered to be of conservation concern in Arkansas. (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Asclepias nyctaginifolia is a western counterpart of the more widespread A. oenotheroides and differs primarily in larger leaves and more robust corona segments. Differences are discussed under the latter species. The most widely used common name, Mohave milkweed, is somewhat misleading as the species is mainly distributed along the northern and eastern margins of the Sonoran Desert and barely enters the Mohave Desert. The species is common throughout the southwestern half of Arizona and is rare in California (San Bernardino County), Nevada (Clark County), and New Mexico (Catron, Grant, and Hidalgo counties). (Discussion copyrighted by Flora of North America; reprinted with permission.) |
Source | FNA vol. 14. | FNA vol. 14. |
Parent taxa | Apocynaceae > Asclepias | Apocynaceae > Asclepias |
Sibling taxa | ||
Name authority | Elliott: Sketch Bot. S. Carolina 1: 321. (1817) | A. Gray: Proc. Amer. Acad. Arts 12: 69. (1876) |
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