Abstract
The spore morphology and wall ultrastructure of Dryopteris filix-mas, D. patula and D. wallichiana from Argentina were studied using light microscope, scanning and transmission electron microscope. The study was carried out with herbarium material from Argentine institutions. Equatorial diameters, polar diameters and laesura length were measured. The spores are monoletes with a rugate ornamentation. The folds are short to long, inflate, irregular in shape and size, and varying from subglobose to elongate. The perispore surface is rugulate. The exospore of all the species analyzed is two-layered in section. Simple and branched channels are also present. The perispore is composed of two layers, the inner one forms the ornamentation and the outer covers all the outer and inner surfaces. Some abnormalities, such as globose, triangular or twisted spores were observed. The morphology and ultrastructure of the species are very similar. The differences observed are related to the length and thickness of the perispore folds. The characteristics of these spores would not provide relevant information to differentiate species or sections within the genus, but can provide information for phylogenetic studies as well as for alterations in the biological cycles.
Highlights
The Dryopteridaceae family is one of the most diverse among leptosporangiate ferns, with 26 genera and an estimated 2115 species of cosmopolitan distribution (PPG I 2016)
About 160 of them are found in Southeast Asia, which seems to be their center of diversity (Sessa et al 2012b), about 15 species are distributed in Central and South America (Prado et al 2014) and 3 species are cited by Ponce & Arana (2016): D. filix-mas (L.) Schott, D. patula (Sw.) Underw
For the Transmission Electron Microscope (TEM) analysis, the material was treated following the technique of Rowley & Nilsson (1972): it was rehydrated with 0.1 M buffer and with 1% Alcian Blue (AB) for 2 hours; the material was fixed with 1% glutaraldehyde + 1% AB in phosphate buffer for 12 hours; it was washed for 15 minutes in phosphate buffer and postfixed with 1% Osmium tetraoxide in water + AB for 2 hours
Summary
The Dryopteridaceae family is one of the most diverse among leptosporangiate ferns, with 26 genera and an estimated 2115 species of cosmopolitan distribution (PPG I 2016). In tropical America, they usually grows in humid mountain forests, cloud forests and lowland rain forests. They grow in areas ranging from sea level to 4000 m, preferably within the 1000 - 2500 m (Tryon & Tryon 1982, Narváez et al 2008). Classifications within the genus have been established on the basis of morphology (Sessa et al 2012b): Ito (1935, 1936) has treated the species of Japan and Taiwan whereas Ching (1938) has done so with those of China, the Himalayas, India and Sri Lanka. An Acad Bras Cienc (2020) 92(Suppl. 2)
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