Plants of the alliance have leaves in pairs or (infrequently) leaves in whorls of three. S. douglasii has two compressed whorls, which appear to be a whorl of six. A few species of the Corytholoma group have leaves which appear to be borne singly at the end of a petiole-like stem.
Most plants of the alliance have hummingbird-pollinated flowers. This results in a common theme: red tubular corollas. There are a few species pollinated by bees and these have white, cream-colored, or lavender flowers. Two or three species are pollinated by bats and have large, sturdy flowers with prominent markings.