Morphoanatomical and histochemical study of seeds of four species of Swartzia (Fabaceae - Papilionoideae) at Tupé Sustainable Development Reserve AM/Brazil

Abstract

Background: In Brazil, Swartzia Schreb. occurs in almost all phytogeographic domains, but the greatest richness of species is concentrated in the Amazon. Question: What are the morphological and anatomical variations of the seeds of species of the Swartzia? Studied species: Swartzia laevicarpa, Swartzia macrocarpa, Swartzia recurva, and Swartzia sericea. Study site and dates: The species were collected in the Sustainable Development Reserve of Tupé - AM Brazil, in 2017 and 2018. Methods: Cross-sections of the seed coat were cut, to observe the characteristics of the seed coat in the hilar region and opposite it. Histochemical tests were performed on the cross-sections of fresh samples, to verify ergastic substances present in the aril, seed coat and cotyledons. Results: The seeds have a smooth and membranous seed coat, partially covered by a spongy aril in Swartzia recurva, filamentous in S. laevicarpa, S. sericea, and S. macrocarpa. Linear hylum, imperceptible micropyle, cryptoradicular embryo, fleshy cotyledons, containing starch, lipids, alkaloids, protein and the rudimentary plumule. Conclusions: Morphological characteristics of the seed, such as shape, color, consistency of the aril and size of the hilum, are important diagnostic characters in the recognition of this species in the field, through its respective seeds; in the same way, the information on soil seed bank is expanded. The presence of fleshy cotyledons indicates and adaptation to the type of environment in which these species occurs, while the knowledge of ergastic substances present in the aril, seed coat and cotyledons, contributes to the understanding of their germinative processes.