Asclepias obovata |
Asclepias macrotis |
|
---|---|---|
pineland milkweed |
long-hood milkweed, longhorn milkweed |
|
Habit | Herbs. | Subshrubs, densely cespitose. |
Stems | 1 (rarely more), erect to spreading, unbranched, 40–70(–200) cm, densely hirtellous to velutinous, not glaucous, rhizomes absent. |
few–numerous, erect to ascending, branched at base, 10–35 cm, minutely puberulent with curved trichomes in a line 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. |
opposite, sessile, with 1 stipular colleter on each side of leaf base; blade filiform, 2.5–7 × 0.05–0.15 cm, membranous, base cuneate, margins revolute, apex acute, mucronate, venation obscure, surfaces glabrous, margins minutely ciliate at base, 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. |
extra-axillary, sessile or pedunculate, 2–7-flowered; peduncle 0–0.8 cm, puberulent with curved trichomes, with 1 caducous bract at the base of each pedicel. |
Pedicels | 10–12 mm, densely hirtellous to velutinous. |
6–10 mm, minutely puberulent with curved trichomes in a line. |
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, 2–2.5 mm, apex acute, glabrous; corolla greenish cream tinged with red, lobes reflexed with spreading tips, oval, 4–5 mm, apex acute, glabrous; gynostegial column 0.5–1 mm; fused anthers brown, cylindric, 1–1.5 mm, wings right-triangular, closed, apical appendages broadly ovate; corona segments cream to greenish cream, reddish brown at base or as a dorsal stripe, subsessile, conduplicate, 4–5 mm, exceeding style apex, apex truncate, long-caudate, crisped, with a proximal tooth on each side, hirtellous, internal appendage falcate, exserted, inflexed towards style apex, hirtellous; style apex shallowly depressed, green. |
Seeds | broadly ovate, 8–9 × 6–7 mm, margin winged, faces smooth; coma 2–5 cm. |
ovate, 6–8 × 2.5–4 mm, margin thickly winged, faces rugulose; coma 2–2.5 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, 4.5–6 × 0.5–0.7 cm, apex attenuate, smooth, glabrous. |
Asclepias obovata |
Asclepias macrotis |
|
Phenology | Flowering May–Sep; fruiting Jul–Oct. | Flowering May–Oct; 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. | Mesas, hills, slopes, flats, canyon rims and bottoms, arroyo margins, limestone, sandstone, shale, rhyolite, gypsum, caliche, cracks in bedrock, talus, gravel and sandy soils, oak, pine-oak, juniper, and pinyon-juniper woodlands, chaparral, shrubby grasslands, desert grasslands, prairies. |
Elevation | 0–200 m. (0–700 ft.) | 1100–2200 m. (3600–7200 ft.) |
Distribution |
AL; AR; FL; GA; LA; MS; OK; SC; TX
|
AZ; CO; NM; OK; TX; Mexico (Chihuahua, Coahuila, 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.) |
With a suffruticose, cespitose, intricately branched habit, the only other milkweed with which Asclepias macrotis can be confused is the rarely encountered A. sperryi, which is restricted to the Big Bend region of Texas in the flora area. Although A. macrotis ranges across western Texas, it appears to be absent from Big Bend; no mixed populations of these species are known, and hybridization is neither known nor suspected. Its distribution in Colorado is limited to the southeastern corner of the state and in Oklahoma to the extreme tip of the Panhandle, in Cimarron County. In Arizona, it is more common but limited to the three southeastern counties: Cochise, Pima, and Santa Cruz. The elongate, curled apices of the corona segments are unique, and the small, drab flowers are quite elegant. (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) | Torrey in W. H. Emory: Rep. U.S. Mex. Bound. 2(1): 164, plate 45, fig. B. (1859) |
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