Desenvolvimento do fruto e da semente de Pteroceltis tatarinowii Maxim. e Trema micrantha (L.) Blume (Cannabaceae)

Abstract

The Cannabaceae family has ten genera and three types of fruit.Trema micrantha and Pteroceltis tatarinowii belong to the family and have drupe and samara-type fruit, respectively. Anatomy studies of the fruit for this family are rare and have importance to classifying the fruit and identifying characters that may be associated with the dispersion syndrome of fruit. Therefore, the objective of this work was to analyze and understand the development of fruit and seed of Pteroceltis tatarinowii e Trema micrantha. Compare the development of those three types of fruit samara, drupe, achene and evaluate if there is a relation between the compounds and the fruit structures to the dispersion syndrome. For this study, several fruits on different development stages, of P. tatarinowii and Trema micrantha, were processed for histological analysis. The histochemical analysis has been done on the mature fruit of P. tatarinowii and for T. micrantha were obtained from literature. The details from Cannabis sativa achene were obtained from literature. The fruit of P. tatarinowii has a uniseriate exocarp with secretory trichomes, non-secretory trichomes, and cystoliths in all stages of development, the mesocarp is distinct in two regions. The outermost elongating and forming the wings and the innermost part has a thickened wall, in the mature fruit the mesocarp is homogeneously formed by spongy parenchyma, the endocarp is uniseriate and formed by macrosclereids until the penultimate stage of development and in the mature fruit, it is reduced and forms a small layer with a lignified cell wall. Trema micrantha has a uniseriate exocarp, with a cuticle and cystolith, a mesocarp divided into three regions at all stages of development, and an endocarp formed by macrosclereids in the mature fruit. The seed of both fruits has a testa and tegmen and an embryo occupying almost the entire seminal cavity. Although the three species had three distinct types of fruit, they had many similarities in ontogeny. The fruits not only provide protection to the seed but also play a fundamental role in attracting biotic dispersion, especially in the supply of food. The anatomical data from this study should contribute to future studies focused on family systematics.