The flowers are fragrant and attractive to many insects. A beautiful metallic-iridescent leaf-beetle, Chrysochus auratus Fabr., is known as the "dogbane beetle" because of its regular association with Apocynum (its larvae feed on the roots).

1. Corolla (5-) 5.5-8 (-9) mm long when mature, with spreading to recurved lobes, pink to rosy (at least in lines within) when fresh; leaves ovate to broadly elliptic, widely spreading or drooping.

A. androsaemifolium

1. Corolla 2.5-4 (-4.5) mm long, with erect lobes when mature, white to greenish when fresh; leaves oblong to broadly lanceolate, ± strongly ascending.

A. cannabinum