Asclepias obovata |
Asclepias amplexicaulis |
|
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pineland milkweed |
blunt-leaf milkweed, blunt-leaf or clasping or sand milkweed, clasping 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 or 2+, erect, unbranched, 35–175 cm, glabrous, glaucous, rhizomes absent. |
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, sessile, with 1 stipular colleter on each side of leaf base; blade broadly ovate or oval to oblong, 6–14 × 3–7 cm, chartaceous, base cordate, clasping, margins often crisped, apex rounded to truncate, emarginate, or obtuse, sometime mucronate, venation eucamptodromous to brochidodromous, surfaces glabrous, glaucous, margins minutely ciliate, 6–16 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. |
terminal (extra-axillary at upper nodes), pedunculate, 18–53-flowered; peduncle occasionally branched, 5–40 cm, glabrous, glaucous, with 1 caducous bract at the base of each pedicel. |
Pedicels | 10–12 mm, densely hirtellous to velutinous. |
20–55 mm, puberulent with curved trichomes. |
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 narrowly lanceolate, 3–5 mm, apex attenuate, sparsely pilosulous to glabrate; corolla green, often tinged red, purple, or bronze, lobes reflexed, lanceolate, 8–11 mm, apex acute, glabrous; gynostegial column 1.5–2.5 mm; fused anthers green, obconic, 2.5–3.5 mm, wings right-triangular, open at base, apical appendages rhomboid; corona segments reddish purple to cream, stipitate, tubular, 4–6 mm, exceeding style apex, apex truncate, erose, glabrous, internal appendage falcate, exserted, sharply inflexed over style apex, glabrous; style apex shallowly depressed, green. |
Seeds | broadly ovate, 8–9 × 6–7 mm, margin winged, faces smooth; coma 2–5 cm. |
ovate, 9–10 × 6–7 mm, margin winged, faces minutely 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, fusiform to narrowly lance-ovoid, 9–16 × 1–2 cm, apex long-acuminate, smooth, pilosulous. |
Asclepias obovata |
Asclepias amplexicaulis |
|
Phenology | Flowering May–Sep; fruiting Jul–Oct. | Flowering Mar–Sep; fruiting (Apr–)May–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. | Dunes, ridges, slopes, sand hills, ravines, sandstone, rarely limestone, sandy, rocky, or silty soils, meadows, pastures, fields, railroad embankments, sand prairies, wet prairies, river banks, open oak woods, barrens, pine-oak forests, pine flatwoods and savannas, forest edges. |
Elevation | 0–200 m. (0–700 ft.) | 0–800 m. (0–2600 ft.) |
Distribution |
AL; AR; FL; GA; LA; MS; OK; SC; TX
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AL; AR; CT; DC; DE; FL; GA; IA; IL; IN; KS; KY; LA; MA; MD; MI; MN; MO; MS; NC; NE; NH; NJ; NY; OH; OK; PA; RI; SC; TN; TX; VA; VT; WI; WV
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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.) |
The common name sand milkweed refers to a strong association of Asclepias amplexicaulis with sandstone substrates and sandy soils. The clasping leaves and long-peduncled terminal inflorescence of A. amplexicaulis are distinctive among all co-occurring milkweeds. Western populations of A. amplexicaulis, primarily from prairies, usually have paler flowers with creamy coronas, whereas those from forest openings in the eastern and southeastern United States usually have pink to maroon coronas. The species is rare on the northwestern and northeastern margins of its range, where it is considered to be of conservation concern in Minnesota, Nebraska, New Hampshire, Rhode Island, Vermont (only in Chittenden County), and West Virginia. Hybrids with A. exaltata, A. purpurascens, and A. syriaca are known, but are local and not documented often. Presumed hybrids can be recognized by possessing intermediate floral and vegetative characteristics. Asclepias × intermedia Vail probably applies to the hybrid with A. syriaca based on Vail’s protologue (A. M. Vail 1904), but the holotype (E. P. Bicknell s.n. [NY]) is damaged, making the assignment tentative. The homonym A. amplexicaulis Michaux was applied to A. humistrata in the past, resulting in some taxonomic confusion between these species and the misidentification of herbarium specimens. (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 | ||
Synonyms | A. obtusifolia | |
Name authority | Elliott: Sketch Bot. S. Carolina 1: 321. (1817) | Smith in J. E. Smith and J. Abbott: Nat. Hist. Lepidopt. Georgia 1: 14, plate 7. (1797) |
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