Structure and chemical nature of intercellular protuberances in Dennstaedtiaceae rhizomes (Polypodiopsida)

Intercellular protuberances (IPs) are projections on the cell surface and have been reported for families of ferns, Gymnosperms, Angiosperms. Data type, chemical composition, distribution these structures among vascular plants still scarce. Here, we investigate occurrence, distribution, type IPs species eight Dennstaedtiaceae genera verify taxonomic significance in family. Rhizomes 23 from field herbaria collections were analyzed by light microscopy scanning electron microscopy. Histochemical tests performed to identify main classes compounds. Two types observed species: strand filament types. They intercellular spaces parenchyma cortex pith regions. Overall, irregularly shaped, with angustate or spheroidal apices. Their polysaccharide nature pectic constitution confirmed histochemical tests. Concerning Pteridium arachnoideum (Kaulf.) Maxon subsp. arachnoideum, phenolic composition. Evidence indicates that originate fragmentation middle lamella they a structural function as well protection against pathogens. In lateral-line aerenchyma, occurrence filament-type may be related larger spacing region, providing greater mechanical resistance. We expanded data Dennstaedtiaceae, which appear notable characters Moreover, presented herein structures. However, unable find links between taxonomy evolution Dennstaedtiaceae. On other hand, different identified clades Dennstaedtioideae (strand-type IPs) Hypolepidoideae (filament-type IPs, exceptions).