Morfo-anatomia e desenvolvimento dos frutos e sementes de três espécies da subfamília Arecoideae (Arecaceae)

Abstract

The main objective of this study was to understand better the tissue layers that compose the fruits and seeds of palms. However, I also undertook a preliminary study on the chemical composition of the fruits as well as the behavior of the plant during its reproductive period. I studied Leopoldinia pulchra (“jará”), Attalea attaleoides (“palha branca”) and Astrocaryum acaule Mart. (“tucumã-í”), respectively in the following areas in the state of Amazonas: flooded forest in the municipality of Iranduba, plateau forest of the MIL1 – Madeireira Itacoatiara Ltda., concession in the municipality of Itacoatiara, and valley-bottom forest in the UFAM Campus (zone east of Manaus). I accompanied fruit development, from the moment of anthesis to maturation. The morphological study was based on samples of fruits in several development phases. Mature fruits were used made in chemical analyses. The time elapsed between the anthesis and the final phase of maturation were 180 days for L. pulchra, 200-220 days for A. attaleoides and 160 days for A. acaule. The fruit of L. pulchra is a monospermous bacca, originated from tricarpellary and pseudomonomerous gynoecium, in which a carpel is developed. Form may be ovoid, lenticular or ellipsoid. The exocarp is flat, lustrous and stuck to the mesocarp until maturity, when it becomes brittle and intense ruby in color. The immature mesocarp is whitish with undifferentiated fibers and turns grayish at maturity. It is constituted of a layer of brachysclereids beneath the subepidermic tissue, followed by parenchymatic tissue densely interrupted by thick groupings of fibers associated with vascular bundles. The endocarp has a locular epidermis associated to the adjacent fibers originating from the mesocarp, and the endosperm is liquid, gelatinous and solid at maturation. The fruit of A. attaleoides is a drupe with two or three seeds, originating from a syncarpous, trilocular and triovulate ovary, with a frequently ovoid form. The exocarp is covered by a red brown indument. The immature mesocarp is fibrous, whitish and, at maturity it is yellow-orange, with a fibrous external layer, an intermediate layer of parenchyma, and an internal layer of woven interrupted parenchymatic bundles of vascular fibers. The endocarp is complex, surrounded on the outside by a layer of woody fiber with an inner locular epidermis and part of tegument, while the middle layers originate from parenchymatic cells differentiated in macrosclereids. In the development of the endosperm there are three distinct phases: initially liquid, passing to gelatinous and becoming solid at maturity. The fruit of A. acaule is predominantly a unisperm drupe, originating from the syncarpous, trilocular and triovulate ovary, it shape varies from obovoid to elliptic. The exocarp is endowed with stomata, has smooth surface, wax-coating and is yellow at maturity. The immature mesocarp is fibrous, mucilaginous and whitish in coloration at maturity it is yellowish, constituted mainly of parenchymatic tissue and vascular fiber. The endocarp and the endosperm are similar to those of A. attaleoides, in terms of origin and constitution. Tannins, silica bodies and starch grains are common in the pericarps of the fruits of the three species.