Palynological analysis of the genus Ctenitis (C. Chr.) C. Chr. (Dryopteridaceae) in the Southern Cone of America.

The spore morphology and wall ultrastructure of 12 species of Ctenitis from Southern Cone of America were studied using light microscope, scanning and transmission electron microscope. The study was carried out with herbarium material from Argentine and Brazilian institutions. Equatorial diameters, polar diameters and laesura length were measured. The spores are monolete with echinate or folded ornamentation. In the echinate type, the spines are conical, with broad base and attenuate apex. In the rugate type, the folds are inflated, linear, sinuous, subglobose or handle-shape. The perispore surface is scabrate, rugulate, microverrucose or psilate. Stratification and ultrastructure in the species analyzed are very similar. The exospore is smooth and two-layered in section. Simple and branched channels are observed mainly in the outer exospore. The perispore is composed of two layers, the inner one forms the ornamentation and the outer covers all the outer and inner surfaces. Immature spores were found in all samples of C. fenestralis. The characteristics of the studied spores like macro-ornamentation, color and fold length provide relevant information to differentiate some species or groups of species within the genus.

Comparative palynological analysis of Lygodium venustum Sw. and L. volubile Sw. (Lygodiaceae).

The genus Lygodium Sw. is one of the few climbing ferns in the world. The spores of L. venustum Sw. and L. volubile Sw. were studied using light, scanning, and transmission electron microscopy. This work is based on herbarium material. The spores are trilete, triangular, with straight to convex sides in polar view. The equatorial diameter is 72-104 µm, and the polar diameter is 64-84 µm. The ornamentation in L. venustum is verrucate-tuberculate while in L. volubile, it is verrucate-tuberculate in the proximal face but with a few ridges on the distal face, where a micro-ornamentation constituted by verrrucae and tubercles is observed. An equatorial ridge is also present. The exospore is two-layered; in L. venustum, it is smooth in contrast with the ornamented exospore of L. volubile. The perispore of the two species analyzed is similar. This wall is four-layered with particular elements arranged radially in the middle layer. On the spores surface of both species, few spheroids are observed. The results introduced in the current study may be useful for the systematics of the genus as well as for phylogenetic purposes.