Largest seed embryo

The largest seed embryo is that of the leguminous tree species Mora oleifera and M. megistosperma, which are large, heavy species native to the rainforests of tropical America. Their seed embryos each consist of two primary leaves or cotyledons (hence are called dicotyledonous seeds), and occupy virtually the entire seed, which in these two species can be up to 18 cm long, 15 cm wide and 8 cm thick, and weigh up to 1 kg.

Traditionally, the angiosperms or flowering plants were divided taxonomically into dicotyledons and monocotyledons, based upon whether the seed embryo possesses two primary leaves (cotyledon) or only one. In more recent years, however, genetic analyses have revealed that several entirely separate angiosperm taxonomic groups all share the dicotyledonous state, which means that it has arisen independently several times during the evolution of angiosperms.