Asclepias obovata |
Asclepias eastwoodiana |
|
---|---|---|
pineland milkweed |
Eastwood's milkweed |
|
Habit | Herbs. | Herbs. |
Stems | 1 (rarely more), erect to spreading, unbranched, 40–70(–200) cm, densely hirtellous to velutinous, not glaucous, rhizomes absent. |
1–6, ascending to decumbent, unbranched or branched near base, 6–30 cm, puberulent with curved trichomes, 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. |
proximally opposite, distally alternate, petiolate, with 0 or 1 stipular colleter on either side of petiole; petiole 2–10 mm, puberulent with curved trichomes; blade narrowly lanceolate to ovate, 2–4.5 × 0.6–3 cm, chartaceous, base cuneate to obtuse, margins entire, apex acute, mucronate, venation eucamptodromous, surfaces strigulose or pilosulous on midvein to glabrate, margins densely ciliate, laminar colleters absent. |
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 and extra-axillary at upper nodes, sessile or pedunculate, 2–25-flowered; peduncle 0–4 cm, puberulent with curved trichomes to glabrate, bracts few. |
Pedicels | 10–12 mm, densely hirtellous to velutinous. |
10–28 mm, pilosulous to 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; calyx lobes elliptic to lanceolate, 2–2.5 mm, apex acute, puberulent with curved trichomes to pilosulous; corolla red-violet, faintly striate, lobes reflexed with spreading tips, oval, 4–5 mm, apex acute, glabrous; gynostegial column 0.2–0.5 mm; fused anthers brown, cylindric, 1.5–2 mm, wings right-triangular, apical appendages ovate; corona segments red-violet dorsally, white proximally, sessile, cupulate, 1.5–2 mm, slightly exceeded by style apex, apex truncate with a proximal tooth on each side, glabrous, internal appendage conical, barely exserted from cavity, glabrous; style apex shallowly depressed, pink to red-violet. |
Seeds | broadly ovate, 8–9 × 6–7 mm, margin winged, faces smooth; coma 2–5 cm. |
not seen. |
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. |
spreading to pendulous on spreading pedicels, lance-ovoid, 3.5–6 × 0.5–1 cm, apex acuminate, smooth, faintly striate, strigose. |
Asclepias obovata |
Asclepias eastwoodiana |
|
Phenology | Flowering May–Sep; fruiting Jul–Oct. | Flowering May–Jun; fruiting Jun. |
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. | Valleys, depressions, flats, slopes, arroyos, dunes, granite, gravel, sandy, calcareous, and clay soils, shrubby grasslands, desert scrub, pinyon-juniper woodlands. |
Elevation | 0–200 m. (0–700 ft.) | 1400–2200 m. (4600–7200 ft.) |
Distribution |
AL; AR; FL; GA; LA; MS; OK; SC; TX
|
NV |
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 eastwoodiana and the next three species (A. ruthiae, A. sanjuanensis, A. uncialis) form a complex of largely allopatric entities that have sometimes been united in a single species, for which the name A. uncialis holds priority (for example, E. Sundell 1994). However, each entity shows genetic, chemical, and subtle morphological distinctions, supporting recognition at the specific rank (M. B. Sady and J. N. Seibert 1991; J. P. Riser et al. 2019). Asclepias eastwoodiana is distinguished from the others by the differences in leaf shape, vestiture, and corona morphology indicated in the key. With A. ruthiae it shares a spreading to pendulous fruit that differs from the typically erect fruits of A. sanjuanensis and A. uncialis. Asclepias eastwoodiana is endemic to valleys in central Nevada (Esmeralda, Lander, Lincoln, Mineral, and Nye counties), where it is considered to be a species of conservation concern, potentially threatened by livestock trampling and mining development. (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) | Barneby: Leafl. W. Bot. 4: 210. (1945) |
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