LEAF ANATOMY IN SANSEVIERIA (AGAVACEAE).

Forty-nine taxa of Sansevieria were examined to provide the first detailed description of leaf anatomy in the genus, as well as to determine the cellular organization of the water-storage tissue present in the central mesophyll of all leaves. Leaf form ranges from flat through cylindrical, with varying degrees of xeromorphic characteristics, including cuticle thickness, stomatal depth, fiber content, and fiber cell development. Mesophyll in all species is divided into an outer region of chlorenchyma and a central region of colorless water-storage tissue. The water-storage tissue comprises a highly branched 3-dimensional network of living cells, among which are many dead, thin-walled water-storage cells. Species with more extreme xeromorphic characteristics tend to have a greater percentage of their water-storage tissue composed of water-storage cells. In 28 taxa, water-storage cells have spiral or reticulate wall bands. These taxa tend to be more xeromorphic. The wall bands may serve an important structural role in drought tolerance.