Aquatic ferns from Viçosa (MG, Brazil): Salviniales (Filicopsida; Tracheophyta).
This work presents the species of Salviniales occurring in the region of Viçosa, MG, Brazil. There, two species occur naturally (Azolla microphylla Kaulf. and Salvinia auriculata Aubl.), three spontaneously (Marsilea ancylopoda A. Braun, S. minima Baker, and S. molesta D.S. Mitch.), and one in cultivation (S. biloba Raddi). Both S. auriculata and S. molesta form dense mats, covering the whole lake areas; S. biloba also forms mats throughout its native distribution. We confirmed the alloploidy (pentaploidy) of S. molesta, due to the production of only hollow sporangia; we speculate aneuploidy for other taxa from Viçosa. We also confirmed the presence of nitrogen-fixing cyanobacterium, Anabaena azollae Strasburger (Nostocaceae), within the fronds of A. microphylla. We provide keys, descriptions, illustrations, taxonomic comments, and updated distribution data for all six taxa. We also propose new characteristics with taxonomic value and new morphological terminology for Salvinia.