The leaf margins normally have spines. Mostly epiphytic species, but the genus Alcantarea has only terrestrial, saxicolous species. The ovary is almost always superior and the fruit is a dehiscent capsule with plumose seeds. There are no spines on the leaf margins. The ovary is inferior and the berry-like fruit has naked seeds.
Most species have spiny leaf margins.
The total number of species in each genus is shown in parentheses.