Leaf architecture and anatomy of eleven species of Mortoniodendron (Malvaceae s.l.)

The genus Mortoniodendron is distributed from southeastern Mexico to Colombia and contains about 18 species of trees and shrubs. The main goal of this study is to describe and compare the leaf architecture and the anatomy of 11 species of Mortoniodendron using cleared leaves and paradermal and transverse leaf sections. All of the species of Mortoniodendron share a simple lamina with an entire margin. The differences among the species include the venation pattern, the relative thickness and course of the secondary veins, the presence or absence of the intersecondary veins, the tertiary vein pattern, the number of branches in veinlets, and the marginal ultimate venation. The leaf anatomy is similar to other species of the Malvaceae s.l.: for example, mucilage cells are common in Mortoniodendron. There are unique attributes of the leaf architecture and anatomy, such as the eucamptodromous venation pattern of M. guatemalense, which facilitates the identification of the species. The species M. palaciosii, M. pentagonum, M. ruizii, M. uxpanapense, and M. sp. nov. share features that suggest that they are closely related.