Common Milkweed

This herbaceous perennial plant is 2-6' tall and unbranched, except sometimes toward the apex, where the flowers occur. The central stem is relative stout, pale green, terete, and usually short-pubescent (less often glabrous). The opposite leaves are up to 8" long and 3½" wide, broadly oblong in shape, and smooth along their margins. The upper leaf surface is pale-medium to dark green and hairless above, while the lower leaf surface is densely covered with woolly hairs that are very short. There is a prominent central vein along the length of each leaf, and finer side veins that radiate outward toward the smooth margins. When either the central stem or leaves are torn, a milky sap oozes out that has variable toxicity in the form of cardiac glycosides.

Umbels of flowers, each about 2½-4" across, emerge from the axils of the upper leaves. These flowers are quite fragrant, with a scent resembling violets or pansies, and they range in color from faded light pink to reddish purple. Each flower is about ¼" across, consisting of 5 reflexed petals and 5 raised hoods with curved horns. The hoods are more light-colored than the petals. The pedicels of the flowers are light green to pale red and hairy. The blooming period lasts about 1-1½ months from early to mid-summer. The seedpods (follicles) are 3-4" long, broadly lanceoloid, and covered with soft prickles and short woolly hairs. At maturity, each seedpod split along one side to release numerous seeds that have large tufts of white hair. Dispersion of seed is by wind. The root system has long creeping rhizomes, promoting the vegetative spread of this plant.