I'm answering my own question. A friend bought two plants from a nursery. They looked funny to me -- the smooth stems and leaves. But this (http://www.wildflower.org/plants/result ... plant=ASRU
) says A. rubra is smooth:
Asclepias rubra L.
Red Milkweed, Tall Pink Bog Milkweed
Asclepiadaceae (Milkweed Family)
Synonyms: Asclepias laurifolia
USDA Symbol: ASRU
USDA Native Status: Native to U.S.
Herbaceous perennial with narrow, mostly Glabrous (Smooth; hairless.) stems 16 to 40 in height. Leaves opposite, ovate or lanceolate, 5-15 cm in length; sessile or nearly so. Inflorescences terminal and axillary from upper leaf nodes in many-flowered umbels. Flowers showy; color varies from lavender to pink to dull-red. Follicles 8-12cm long.