Morphological and anatomical characteristics and temporal pattern of initial growth in Astrocaryum acaule Mart

Abstract

Astrocaryum acaule Mart. is a palm with underground stem, common in lowland forests, known in Brazil as tucumã-í. The objective of this work was to perform the description and characterization of seeds and of the seedling emergence process, revealing morphological and anatomical patterns of A. acaule. Seedlings were obtained by sowing in vermiculite. The seed is spherical, with variations in shape and size according to the number of seeds in the fruit. Germination is adjacent, with formation of a coleoptile above the cotyledonary sheath. The germinative bud is emitted within between 30 and 130 days. The proximal and distal regions differentiate with growth, forming the seedling and the haustorium that transfers reserves through the reduced apocole. The initial root system differs in the hypocotyl-radicle region, below the insertion of leaf primordia, forming a lateral root and a late primary root. The first eophyll is expanded 120 days after the protrusion of the germinative button, with aculeate petiole, amphistomatic leaf blade, papillose epidermis, homogeneous mesophyll, and vascular system covered by fibers. Morphoanatomical characters reported in this study increase our knowledge about Amazonian palms and on organogenesis in their early stages of growth.