Morphology and ultrastructure of the spores of Dennstaedtiaceae from North West Argentina

The spores of Dennstaedtiaceae species that grow in North West Argentina were analysed. These are: Dennstaedtia cicutaria (Swartz) Moore, Dennstaedtia glauca (Cavanilles) C. Christensen ex Looser, Dennstaedtia globulifera (Poiret) Hieronymus, Hypolepis repens (L.) C. Presl and Pteridium psittacinum (C. Presl) Maxon. LM, SEM and TEM were used in this study. Two types of spores were recognised: monolete spores in Hypolepis and trilete spores in Dennstaedtia and Pteridium. The exospore is homogeneous and apparently double-layered in all the studied spores. According to the plane of section, radial channels, simple or ramified, and others associated to the laesurae are visible in the exospore. The exospore surface is smooth in Dennstaedtia species, irregular in Pteridium and dentate-papillate in Hypolepis. The perispore is single or double-layered with a microlacunouse ultrastructure. The perispore layers can be distinguished by their different contrast, structure and thickness. The perispore sculpture varies from echinulate-echinate to verrucate-ridged. General characteristics like spore type, ornamentation and laesurae features as well as ultrastructural ones like the exospore surface and the number of perispore layers could be useful for systematic purposes.