Seed structure and initial development of Byrsonima basiloba Juss. (Malpighiaceae)

Abstract

Byrsonima basiloba Juss. is a fast growing shrub that produces edible and juicy fruits. This research studied the morphology and anatomy of seeds and seedlings. The hard endocarp was crested and triloculate, with one seed per locule. B. basiloba seed was composed of a testa and a tegmen with residual endosperm. The embryo was ivory, with long, foliaceous, circinate, anisophyllous cotyledons with disjointed apices. The embryonary axis was short, straight and occupied a small portion of the seed with short epicotyl, and radicle with a rudimentary root cap. In the seedlings, it was possible to differentiate the protoderm, procambium and ground meristem in the elongation zone. The differentiation process in this species occurred early in the embryo. Leaf primordia surrounded the shoot apical meristem, which contained a developing parenchyma, epidermis with trichomes, and the vascular system already partially differentiated, with xylem vessels with helical thickening. The stem/root transition region, which originated the xylopodium in the adult plant, was oblique to the stem axis. Cotyledons and eophylls were amphistomatic. The anatomical description can help with taxonomic identification of the species in the field, as well as to provide a guide to choosing explants for in vitro cultivation protocols.