Whorled Milkweed

This perennial herbaceous plant is ½–2' tall and more or less erect; it is either unbranched or sparingly branched along the upper half of its central stem. The central stem is yellowish green or medium green and terete; it has vertical lines of short pubescence. Whorls of 4-6 leaves occur along the nodes of the central stem; because the internodes of this stem are fairly short, these leaves are produced in abundance. Relative to the orientation of the central stem, the leaves are usually ascending, although sometimes they are widely spreading or drooping. The leaves are 2-3" long, 2-3 mm. across, and linear in shape; their margins are entire (toothless) and strongly revolute (rolled downward). Sometimes whorls of smaller secondary leaves are produced from short lateral stems that develop from the axils of leaves along the central stem. The upper leaf surfaces are yellowish green or medium green and glabrous to sparsely short-pubescent; they are narrowly grooved along the middle where the midribs occur. The lower leaf surfaces are whitish green and short-pubescent; they are partially obscured by the rolled leaf margins. The leaves are sessile or they have very short petioles (less than 2 mm. long). From the axils of middle to upper leaves, umbels of flowers are produced on short peduncles (flowering stalks); there can be 1-4 umbels of flowers at each node. Individual umbels span ¾–1½" across, consisting of 7-20 pedicellate flowers.