Comparative anatomy of the roots in development of nine epiphytes monocots from Brazilian Atlantic Forest/ Anatomia comparada das raízes em desenvolvimento de nove monocotiledôneas epífitas da Mata Atlântica Brasileira

Abstract

This study describes and compares root anatomical adaptations in nine monocots: Orchidaceae (Brasiliorchis chrysantha, Gomesa flexuosa, Isochilus linearis, Leptotes bicolor and Trichocentrum pumilum), Bromeliaceae (Aechmea distichantha, Billbergia nutans and Vriesea flava) and Araceae (Philodendron propinquum) epiphytes in Parana state, Brazil. Orchidaceae and Bromeliaceae have velamen radicum. Evident exodermis and endodermis in all species, cortex in the Bromeliaceae divided in three parenchyma. The immature and mature regions of the roots are different between species. Anatomical characteristics of roots related to epiphytism, such as velamen, tilosome, thick exodermis and endodermis, tracheoid idioblasts, idioblasts with raphides and aerenchyma are presents. In species that grow in the sunniest strata, it was observed that the deposition of lignin in the cell wall of the exoderm and endoderm in "O" already occurs just above the differentiated region from the primary meristems. The number of strata of the velamen was higher in these species, reaffirming that the environmental pressure throughout the evolutionary process selected genotypes that are more resistant to conditions with less water availability