This study was carried out with the objective of selecting leaf anatomical characters that can help the taxonomy of Pteridaceae species growing in the PERD. During a preliminary survey, carried out in PERD, 57 species of ferns within 27 genera from 15 families were collected. The most representative family was Pteridaceae, with 17 species distributed in four genera (Adiantum, Hemionitis, Pityrogramma and Pteris). The leaves of these species showed glabrous, hairy or scaled petioles with unistratified epidermis and cortex composed by parenchyma and sclerenchyma. One meristele, in Pteris and Hemionitis, and two or three meristeles in Adiantum and Pityrogramma represent the petiole vascular system. In the distal region, these meristeles are classified in Adiantum as "Onoclea" and "Asterochlaena" types, in Hemionitis as "Grammitis" type, in Pityrogramma as "Onoclea" type, and in Pteris as "Loxsoma" and "Pteris podophylla" types. Leaf blade showed an uniestratified epidermis with idioblasts (sclereides). Idioblasts were parallel, oblique or restricted to veins in Adiantum and Pityrogramma, and reinforcing the leaf margins in Pteris. Idioblasts were absent only in Hemionitis. In some species, leaf blades were hairy or scaled. Anomocytic stomata sometimes associated to diacytic type were observed in the leaf abaxial surface in Adiantum, Hemionitis and Pityrogramma. In Pteris, stomata polocytic occur associated to copolocytic type. The mesophyll was homogeneous with "armed" cells in most Adiantum species or with lobed cells tending to isodiametric in the other genera. Hairs or scales, stomata type, presence and idioblasts distribution in the epidermis, type and disposition of petiole vascular tissue were the most relevant anatomical characters for the Pteridaceae identification in the PERD.
Pteridaceae; foliar anatomy; State Park of Rio Doce (MG)
