Asclepias longifolia

Herbs. Stems 1–few, spreading to decumbent, unbranched, 25–70 cm, puberulent with curved trichomes, not glaucous, rhizomes absent. Leaves oppo­site or alternate, sessile or petiolate, with 1 or 2 stipular colleters on each side of petiole, also in axil; petiole 0–2 mm, puberulent with curved trichomes; blade linear to linear-lanceolate, 5–18 × 0.2–1 cm, chartaceous, base cuneate, margins entire, apex acute to attenuate, sometimes mucronate, venation brochidodromous, sur­faces scabridulous to puberulent with curved tri­chomes, especially on veins, margins ciliate, laminar colleters absent. Inflorescences terminal and extra-axillary at upper nodes, sessile or pedunculate, 13–28(–36)-flowered; peduncle 0–6 cm, puberulent with curved trichomes, with 1 caducous bract at the base of each pedicel. Pedicels 9–16 mm, puberulent with curved trichomes. Flowers erect to spreading; calyx lobes narrowly lanceolate, 1.5–2 mm, apex acute, puberulent with curved trichomes; corolla white to greenish cream, purple at lobe tips, lobes reflexed, oblong, 3–5 mm, apex obtuse, glabrous; gynostegial column 0.2–0.5 mm; fused anthers green or brown, cylindric, 1–1.5 mm, wings triangular to trapezoidal, widest at middle, slightly open at tip, apical appendages ovate; corona segments pinkish lavender to red-violet, often with white apex, often a darker red-violet stripe or at base, sessile, laminar, strongly dorsally compressed, margins incurved, appressed to column, curved to sub­saccate, 2–2.5 mm, exceeding point of anther wings, greatly exceeded by style apex, apex obtuse to truncate, gla­brous, internal appendage absent or obscure, glabrous; style apex shallowly depressed, greenish cream to green. Follicles erect on upcurved pedicels, narrowly fusiform, 8–13.5 × 0.7–1.2 cm, apex attenuate, smooth, puberulent with curved trichomes. Seeds ovate, 11–12 × 7–8 mm, margin winged, faces smooth; coma 4–5 cm.

Phenology: Flowering (Jan–)Feb–Sep(–Oct); fruiting Apr–Aug.
Habitat: Bogs, swamps, flats, ditches, depressions, pond edges, sandy, clay, and rocky soils, wet prairies, pine flatwoods, oak woodlands, savannas, pastures, often following fires.
Elevation: 0–100 m.

Distribution

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• Legacy Map

Ala., Del., Fla., Ga., La., Miss., N.C., S.C., Va.

Discussion

Asclepias longifolia has sometimes been treated to include A. hirtella as conspecific, as discussed under that species. As circumscribed here, the distribution of A. longifolia extends along the Atlantic Coastal Plain south of Delaware to Florida and westward to the Mississppi River. Reports of A. longifolia from west of the Mississippi River in Louisiana and in Texas are assigned here to A. hirtella. Hence, the range of A. longifolia in Louisiana is extremely limited, and the conservation status of this species warrants assessment in that state (Livingston, Saint Helena, Saint Tammany, Tangipahoa, and Washington parishes). Reports of A. longifolia from Maryland and West Virginia have not been confirmed, and the species is considered extirpated from Delaware. Otherwise, it is rare at the northern extent of its range and considered to be of conservation concern in North Carolina and Virginia (Greensville and Prince George counties).

Selected References

None.

Lower Taxa

None.