Agradecimentos: This study was financed in part by the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - Brasil (CAPES) - Finance Code 001. Juliana Lischka Sampaio Mayer thank FAPESP (2015/26479-6), FAEPEX 0944/14, CNPq (447453/2014-9), and CNPQ (310184/2016-9) for funding support. We thank The Espaço da Escrita - Pró-Reitoria de Pesquisa - UNICAMP - for the language services provided and the access to equipment and assistance provided by the Electron Microscope Laboratory (LME/UNICAMP). We thank the Instituto Florestal (Parque Estadual da Serra do Mar, Núcleo Santa Virginia and Núcleo Picinguaba) for the development of the study on protected public land and Carlos Eduardo Pereira Nunes for his help in field activities. Ver menos

Abstract: The number of integuments found in angiosperm ovules is variable. In orchids, most species show bitegmic ovules, except for some mycoheterotrophic species that show ovules with only one integument. Analysis of ovules and the development of the seed coat provide important information regarding functional aspects such as dispersal and seed germination. This study aimed to analyze the origin and development of the seed coat of the mycoheterotrophic orchid Pogoniopsis schenckii and to compare this development with that of other photosynthetic species of the family. Flowers and fruits at different stages of development were collected, and the usual methodology for performing anatomical studies, scanning microscopy, and transmission microscopy following established protocols. P. schenckii have ategmic ovules, while the other species are bitegmic. No evidence of integument formation at any stage of development was found through anatomical studies. The reduction of integuments found in the ovules could facilitate fertilization in this species. The seeds of P. schenckii, Vanilla planifolia, and V. palmarum have hard seed coats, while the other species have seed coats formed by the testa alone, making them thin and transparent. P. schenckii, in contrast to the other species analyzed, has a seed coat that originates from the nucellar epidermis, while in other species, the seed coat originates from the outer integument Ver menos