Biogeographic Insights in Central American Cycad Biology

Cycads (Cycadophyta) are dioecious, palm-like, gymnosperm (non-flowering seed plants) trees and shrubs found broadly across the tropical belt of the world (Fig. 1). Cycads are veritable living fossils once thought to date from the Mesozoic as early as 280 million years ago (mya); however, recent reevaluation of the fossil evidence indicates they originated in the upper Paleozoic, more than 300 mya (Pott et al., 2010). They predated, and were contemporaneous with, the dinosaurs and have survived to the present. As a group, the cycads have been systematically restructured, making use of morphological and molecular characters and cladistic analysis (Caputo et al., 2004). Three families are currently considered valid (Cycadaceae, Stangeriaceae, and Zamiaceae), with a world total of about 330 described species (Osborne et al., 2012). Cycas and Zamia are the most widely distributed and researched genera.