Stomata of Ephedra are haplocheilic, monocyclic and tetracytic and occur in furrows, which alternate with non-stomatiferous bands. Species vary in stomatal opening shape, number of stomatal rows per furrow, epidermal cell shape, position of cuticular flanges, and shape of papillae. Leaf venation patterns may be bi- or trifasciculate. Natural interspecific hybridization and polyploidization are thought to play a role in the evolution of New World ephedras.
Cuticular characters confirm the position and parentage of the two interspecific hybrids, E .
Chromosome numbers are available for 15 species. These patterns are further tested against O. Stapf's long-standing classification system.