Anatomia foliar de espécies de Aspleniaceae e Polypodiaceae (Monilófitas) ocorrentes no Parque Estadual da Serra do Brigadeiro, MG, Brasil / Leaf anatomy of Aspleniaceae and Polypodiaceae (Monilophytes) species occurring in the Parque Estadual da Serra do Brigadeiro, MG, Brazil

AUTOR(ES)
DATA DE PUBLICAÇÃO

2009

RESUMO

Pteridophyta is a term used to denominate vascular plants lacking seeds that are dispersed by spores, with a life cycle characterized by two distinct phases: a gametophytic and a sporophytic phase. There are approximately12, 240 fern species displaying great diversity in wet tropical regions. In Brazil, 1,200 to 1,300 species are estimated to exist, with at least 50% of this total occurring in the state of Minas Gerais. Morphology and anatomy studies are fundamental to help elucidate the taxonomic problems found in the different groups of vascular plants. Considering the limited information on the anatomy of the monilophytes, an anatomic characterization of the Aspleniaceae and Polypodiaceae species occurring in the Parque Estadual da Serra do Brigadeiro (PESB) was conducted to select the relevant characters for species identification. Fertile botanical material was collected and placed at the VIC Herbarium of the Universidade Federal de Viçosa. Diaphanization and transversal cuts of the median region of the foliar blade and of the proximal, median, and distal regions of the petiole were performed. The material was processed, stained and mounted according to specific methodology. Asplenium species present uniseriate epidermis and predominantly polocytic or anomocytic stomata. Hairs were observed only in A. pseudonitidum. Mesophyll is homogeneous in most of the species studied with braciform or lobed cells. All the species studied presented dycotomic venation, with free extremities. The petiole presents uniseriate epidermis; hairs were observed in A. jucundum, A. pseudonitidum and A. harpeodes and scales in A. oligophyllum and A. feei. The vascular system of the petiole varied significantly among the species studied, presenting varied number of meristeles throughout the extension and xylem with different shapes (“C”, “X”,”V” or hipocamppus-shaped). The Polypodiaceae species present foliar blade with uniseriate epidermis. In Niphidium crassifolium and Microgramma squamulosa , the presence of hypodermis was verified. Trichomes are present in all the species studied, except in M. squamulosa. Polocytic and copolocytic stomata can be verified in Campyloneurum and Serpocaulon, anomocytic stomata in Pecluma, Pleopeltis and M. squamulosa and diacytic stomata in N. crassifolium. The mesophyll is homogeneous in most of the species analyzed, only in Pleopeltis it is dorsiventral. Regarding the venation pattern, Pecluma presents open venation, with reticulated venation in the other genera. The petiole presents uniseriate epidermis with scales in Pleopeltis and C. repens and hair in Pecluma. Regarding the petiole’s vascular system, a variable number of meristeles was verified, with rearrangements occurring as a result of the fusion of the meristeles towards the distal region of the petiole. Among the characters analyzed, type of stomata, type of trichomes, foliar blade and petiole, venation pattern and petiole vascularization can be considered promising characters for the identification of the genera and species of Aspleniaceae and Polypodiaceae occurring in the PESB.

ASSUNTO(S)

botanica anatomia vegetal aspleniaceae aspleniaceae plant anatomy polypodiaceae polypodiaceae

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