Asclepias obovata |
Asclepias labriformis |
|
---|---|---|
pineland milkweed |
Utah milkweed, Utah or labriform or Jones' or poison 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, erect, unbranched (rarely distally), 15–70 cm, sparsely puberulent with curved trichomes to glabrate, 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. |
alternate (subopposite), sessile or petiolate, with 1 or 2 stipular colleters on each side of petiole plus 4–8 in axil; petiole 0–7 mm, glabrous; blade linear-lanceolate to lanceolate, often falcate, 6–14.5 × 0.5–2 cm, chartaceous, base cuneate, margins entire, apex attenuate to acute, mucronate, venation brochidodromous (often faintly), surfaces glabrous, midvein sometimes sparsely puberulent with curved trichomes abaxially, margins eciliate, 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, pedunculate, 6–28-flowered; peduncle 0.2–2.5 cm, tomentose to glabrate, with 1 caducous bract at the base of each pedicel. |
Pedicels | 10–12 mm, densely hirtellous to velutinous. |
15–25 mm, tomentose to glabrate. |
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 to pendent; calyx lobes lanceolate, 3–4 mm, apex acute, sparsely pilose or tomentulose to glabrate; corolla ochroleucous, lobes reflexed, tips sometimes spreading, oval to elliptic, 6–7 mm, apex acute, glabrous abaxially, minutely hirtellous at base adaxially; gynostegial column 1–1.5 mm; fused anthers green to yellowish green, obconic, 1.5–2 mm, wings narrowly right-triangular, tip distended, closed, apical appendages ovate; corona segments ochroleucous to cream, substipitate, conduplicate, dorsally rounded, nearly tubular, 2.5–3.5 mm, slightly exceeding style apex, apex truncate with proximal tooth on each side, glabrous, internal appendage falcate, exserted, sharply inflexed over style apex, glabrous; style apex shallowly depressed, cream or green. |
Seeds | broadly ovate, 8–9 × 6–7 mm, margin winged, faces smooth; coma 2–5 cm. |
ovate to oval, 12–13 × 8–9 mm, margin winged, faces obscurely rugulose to smooth; coma 1.5–2 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. |
pendulous on spreading to pendulous pedicels, ovoid, 3.5–5.5 × 1.2–2 cm, apex acuminate, smooth, tomentulose to glabrate. |
Asclepias obovata |
Asclepias labriformis |
|
Phenology | Flowering May–Sep; fruiting Jul–Oct. | Flowering May–Aug; fruiting Jun–Oct. |
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, flats, terraces, bluffs, ditches, sandstone, shale, siltstone, gypsum, sandy, gravel, and clay soils, riparian and juniper woods, desert scrub. |
Elevation | 0–200 m. (0–700 ft.) | 1300–2000 m. (4300–6600 ft.) |
Distribution |
AL; AR; FL; GA; LA; MS; OK; SC; TX
|
UT |
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 labriformis is endemic to Utah (Emery, Garfield, Grand, Uintah, and Wayne counties) and is found in a remarkably narrow northeast–southwest band from the terraces surrounding the San Rafael Swell west of Green River, across Waterpocket Fold, to arroyo beds below the Kaiparowits Plateau southeast of Escalante. It shares pendulous follicles with several other milkweed species inhabiting sandy habitats, such as its close relative A. welshii, and more distant relatives A. cutleri and A. subulata. Asclepias labriformis is reputed to be one of the milkweeds that is most poisonous to livestock (J. M. Benson et al. 1979). (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) | M. E. Jones: Proc. Calif. Acad. Sci., ser. 2, 5: 708. (1895) |
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