The features of cotyledon areoles in Leguminosae and their systematic utility

Abstract

The cotyledon areole, which is a spot with granular projections of epidermal cells, appears on the abaxial surface and on the midvein of some legume seed cotyledons. The distribution and systematic utility of cotyledon areoles were studied by observation of 132 legume species, which represent 100 genera and are classified into 34 tribes of three subfamilies, i.e., Caesalpinioideae, Mimosoideae, and Papilionoideae. The cotyledon areole is found in many species of Papilionoideae but not in the other two subfamilies. Presence of a cotyledon areole is presumed to be an apomorphic character state in Papilionoideae from the outgroup rule.