Although the taxonomy is not certain, most authors divide the species into four varieties: var.

Previous treatments of the species divided it into three varieties.

The species is generally divided into two varieties.

Some authorities divide the species into two varieties, var.

This species was previously divided into two varieties.

P. s. serotina is sometimes further divided into four varieties, var.

The species is divided into two rare varieties, each with a limited occurrence on opposite sides of the Bay Area.

It is sometimes divided into two varieties, Fraxinus pennsylvanica var.

This species may be divided into two varieties, var.

The cactus may have yellow or pink flowers; the species is sometimes divided into two varieties on the basis of flower color.