Asclepias obovata |
Asclepias ovalifolia |
|
---|---|---|
pineland milkweed |
asclépiade à feuilles ovées, oval-leaf 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, erect, unbranched, 30–70 cm, densely puberulent with curved trichomes or pilosulous to tomentose, 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. |
opposite, petiolate, with 1 or 2 stipular colleters on each side of petiole; petiole 3–10 mm, densely pilosulous to tomentose; blade broadly ovate to oval or narrowly elliptic, 3–9 × 1.5–4.5 cm, chartaceous, base obtuse or rounded to truncate, margins entire, apex acute to obtuse, mucronate, venation brochidodromous, surfaces pilosulous abaxially, sparsely so adaxially except on veins, margins ciliate, 4–16 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 at upper nodes, sessile or pedunculate, 5–21-flowered; peduncle 0–7 cm, densely pilosulous to tomentose, with 1 caducous bract at the base of each pedicel. |
Pedicels | 10–12 mm, densely hirtellous to velutinous. |
12–22 mm, densely pilosulous to tomentose. |
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 spreading; calyx lobes lanceolate, 2–3 mm, apex acute, densely pilosulous; corolla cream to yellowish, lobes reflexed with spreading tips, elliptic, 5–7 mm, apex acute, pilosulous abaxially at apex, glabrous adaxially; gynostegial column 0.2–0.5 mm; fused anthers green, cylindric, 1.5–2 mm, wings right-triangular, closed, apical appendages ovate; corona segments cream to yellowish, subsessile, conduplicate, dorsally flattened, 3–4 mm, exceeding style apex, apex acute with proximal tooth on each side, glabrous, internal appendage falcate, exserted, sharply inflexed to ascending over style apex, glabrous; style apex shallowly depressed, cream to pinkish. |
Seeds | broadly ovate, 8–9 × 6–7 mm, margin winged, faces smooth; coma 2–5 cm. |
ovate, 5–6 × 3.5–4.5 mm, margin winged, faces rugulose; coma 2.5–3 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, 5–8 × 1.2–2 cm, apex acute to apiculate, smooth, densely pilosulous to tomentose. |
Asclepias obovata |
Asclepias ovalifolia |
|
Phenology | Flowering May–Sep; fruiting Jul–Oct. | Flowering May–Aug; fruiting Jul–Sep. |
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. | Hills, slopes, ravines, bluffs, ridges, dunes, coulees, ditches, lake shores, sandstone, sandy, rocky, and clay soils, prairies, shrubby grasslands, aspen woods, oak savannas, oak woods, pine-oak and pine forests. |
Elevation | 0–200 m. (0–700 ft.) | 300–1600 m. (1000–5200 ft.) |
Distribution |
AL; AR; FL; GA; LA; MS; OK; SC; TX
|
IA; IL; MI; MN; MT; ND; SD; WI; WY; AB; MB; ON; SK
|
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 ovalifolia is the northernmost-ranging species in the genus, and over much of its range co-occurs with at most one other species of Asclepias. The quality of its habitat has been degraded by woody encroachment, presumably resulting from fire suppression. It appears to be secure in the core of its range in Minnesota, North Dakota, Manitoba, and Saskatchewan. Elsewhere there are conservation concerns, as in Illinois (Cook, Kankakee, Kendall, Lake, and McHenry counties), Michigan (Lake and Menominee counties), Montana (Carter and Sheridan counties), Wyoming (Crook County), and Ontario. Asclepias ovalifolia was collected in 1915 in British Columbia in a valley of the Columbia Mountains (Bain. s.n. [UBC]), far disjunct from the species’ range east of the Rocky Mountains. The occurrence has been considered to be adventive and not persistent (F. Lomer, pers. comm.). It has been reported from Nebraska based on the original determination of what became the type specimen of A. hallii; it is not known to have ever occurred in that state. Hybrids with A. syriaca are known, but appear to be rare, and can be recognized by possession of intermediate floral and vegetative traits. (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) | Decaisne in A. P. de Candolle and A. L. P. P. de Candolle: Prodr. 8: 567. (1844) |
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