Description
Whorled milkweed is a perennial herb arising from a fibrous rootcrown. The 3.5-9 dm stems are solitary to few, simple or sparingly branched, and usually sparsely hairy. The leaves are whorled or nearly so, sessile, and linear to thread-like (1.5-8 cm x 0.5-2 mm). The inflorescences are 6-20 flowered and found in the upper leaf axils. The flowers are 5.5-7.5 mm tall, with green or purple-tinged sepals, and white to greenish-purple tinged petals. The "eye" is greenish-white, and the horns arch over the anther head. The fruits are narrowly spindle shaped (8-10.5 cm x 6-8 mm), ascending to erect, sparsely hairy, and smooth (Great Plains Flora 1986, Dorn 2001).
Habitat
Asclepias verticillata grows in "Ridges, slopes, flats, glades, bluffs, dunes, sandhills, streamsides, wet meadows and depressions, lake shores, sandstone, limestone, granite, serpentine, dolomite, shale, sandy, clay, and rocky soils, prairies, pine flatwoods and barrens, pine and oak scrubs, oak and oak-hickory woodlands, pine, pine-oak and pine-mixed-hardwood forests, forest edges" (FNA 2023).