Asclepias obovata |
Asclepias sanjuanensis |
|
---|---|---|
pineland milkweed |
San Juan milkweed |
|
Habit | Herbs. | Herbs. |
Stems | 1 (rarely more), erect to spreading, unbranched, 40–70(–200) cm, densely hirtellous to velutinous, not glaucous, rhizomes absent. |
1–8, decumbent, unbranched or branched near base, 4–13 cm, densely 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. |
opposite and alternate, petiolate, with 0 or 1 stipular colleter on either side of petiole; petiole 2–5 mm, margins puberulent with curved trichomes; blade lanceolate to ovate, 2–5 × 0.5–2 cm, chartaceous, base obtuse to cuneate, margins entire, apex acute to attenuate, venation eucamptodromous, surfaces sparsely pilosulous to glabrate, persistent on veins, 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, 3–8-flowered, bracts few. |
Pedicels | 10–12 mm, densely hirtellous to velutinous. |
11–24 mm, densely pilosulous. |
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, 2–2.5 mm, apex acute, pilose; corolla red-violet, 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 narrowly right-triangular, apical appendages ovate, erose; corona segments red-violet dorsally, white to orange proximally, sessile, cupulate, 1.5–2 mm, slightly exceeded by style apex, apex truncate with a proximal tooth on each side, glabrous, internal appendage falcate, 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. |
broadly ovate, 8–9 × 6–7 mm, margin winged, erose, faces densely rugulose, lepidote; coma 1–1.5 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, ovoid, 3–5 × 0.7–1 cm, apex acuminate, smooth, pilosulous to tomentulose. |
Asclepias obovata |
Asclepias sanjuanensis |
|
Phenology | Flowering May–Sep; fruiting Jul–Oct. | Flowering Apr–May; fruiting May–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. | Slopes, ridges, arroyos, sandstone, sandy, silty, and rocky soils, juniper and pinyon-juniper woodlands, shrubby grasslands, desert scrub. |
Elevation | 0–200 m. (0–700 ft.) | 1400–1800 m. (4600–5900 ft.) |
Distribution |
AL; AR; FL; GA; LA; MS; OK; SC; TX
|
AZ; NM; 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.) |
As discussed under Asclepias eastwoodiana, A. sanjuanensis is part of a complex of four species sometimes recognized as a single species. The range of A. sanjuanensis is larger than initially realized, extending across northwestern Arizona (Apache and Navajo counties) and barely entering southeastern Utah (San Juan County), as discussed under A. ruthiae. These two species are completely allopatric. In New Mexico, A. sanjuanensis is restricted to San Juan County. (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) | K. D. Heil: J. M. Porter & S. L. Welsh, Great Basin Naturalist 49: 100, fig. 1. (1989) |
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