Southern or green milkweed

Herbs, latex clear. Stems 1 (rarely 2), erect, unbranched, 25–75 cm, minutely puberulent in a line with curved trichomes to glabrate, not glaucous, rhizomes absent. Leaves opposite, sessile, with 1 or 2 stipular colleters on each side of leaf base; blade linear to filiform, 4.5–9 × 0.15–0.25 cm, membranous, base cuneate, margins revolute, apex acute, mucronate, venation obscure, surfaces glabrous, margins sparsely ciliate to glabrate, laminar colleters absent. Inflorescences extra-axillary at upper nodes, pedunculate, 4–15-flowered; peduncle 0.8–2 cm, minutely puberulent in a line with curved trichomes, with 1 caducous bract at the base of each pedicel. Pedicels 7–13 mm, minutely puberulent in a line with curved trichomes. Flowers erect to spreading; calyx lobes lanceolate, 1.5–2.5 mm, apex acute, glabrous; corolla green, tinged brown, lobes reflexed with spreading tips, elliptic, 3–5 mm, apex acute to obtuse, sometimes emarginate, glabrous; gynostegial column 0.8–1 mm; fused anthers green and brown, cylindric, 1.5–2 mm, wings right-triangular, closed, apical appendages ovate; corona segments cream, tinged brown or green, stipitate, conduplicate and dorsally rounded, 3–4 mm, slightly exceeding style apex, apex acute, spreading, with a proximal tooth on each side, glabrous, internal appendage falcate, exserted, arching towards style apex, glabrous; style apex shallowly depressed, green. Follicles erect on straight pedicels, fusiform, 9–12.5 × 0.6–0.9 cm, apex long-acuminate, smooth, glabrous. Seeds ovate, 8–9 × 5–6 mm, margin winged, faces minutely and sparsely rugulose; coma 2.5–3 cm.

Flowering Apr–Sep; fruiting Jun–Oct. Wet meadows, pine savannas, pine flatwoods, often following fires; of conservation concern; 0–50 m; Ala., Fla.

Similarities among Asclepias cinerea, A. feayi, and A. viridula are discussed under those species; all three are slender, cryptic when not in flower, and appear to emerge and flower in response to precipitation and fire events. Asclepias viridula is perhaps the most cryptic of the three, by virtue of its green corollas, and it is the most limited in range. It is typically found in wetter sites than co-occurring A. cinerea. Asclepias viridula is found disjunctly in northeastern Florida and the Florida Panhandle. Its range barely crosses into Alabama, where it is known from a single site in Houston County. Reports from Georgia are probably based on misidentifications—no specimens are known, and further searches for A. viridula in Georgia are war­ranted. It is considered to be of conservation concern throughout its range. Although not listed as a threatened or endangered species under the ESA in the United States, the number of populations is low and merits further study of population persistence and viability.