Seedling morphology of three sympatric savanna species of Byrsonima: First evidence of cryptogeal germination in Malpighiaceae and an overlooked seedling type in eudicots

Abstract

Byrsonima crassifolia (L.) Kunth, B. coccolobifolia Kunth and B. verbascifolia (L.) DC. (Malpighicaceae) are sympatric species with high ecological importance in the Roraima savannas of northern Brazil. The three species can be distinguished by seedling characters. The phanerocotylar, epigeal, foliaceous seedling of B. crassifolia is similar to other forest species in the genus. On the other hand, both B. coccolobifolia and B. verbascifolia have phanerocotylar, hypogeal, foliaceous seedlings, representing a newly defined seedling group among eudicot seedling types. Byrsonima verbascifolia has a reduced epicotyl and short subsequent internodes, whereas the long cotyledonary petioles are diagnostic for B. coccolobifolia. Both B. coccolobifolia and B. verbascifolia have cryptogeal germination, which involves characters that presumably protect the plumule from the recurrent fires they are subjected in savannas (e.g., plumule burying, cotyledonary node below the soil surface, and fusion of cotyledonary petioles). This is the first report of cryptogeal germination in the Malpighiaceae as well as in Neotropical eudicots.