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The soil spore bank of ferns is a biotic component of plant communities, important for regeneration processes, population dynamics, and conservation programs. Each year it is enriched when new units are incorporated, and impoverished when they are lost by predation, loss of viability, or by germination. Soil was collected in three microhabitats of the gallery forest of the Panga Stream, at four depths, in the wet and the dry seasons. In general, independent of the season, ‘dike’ samples presented lower numbers of viable spores when compared to samples from the ‘middle’ and ‘edge’ of the forest. The number of viable spores and the number of fern species represented decreased with depth. At the end of the dry season, the number of viable spores decreased only in the first centimeters of the soil. Viable spores of thirteen terrestrial species were registered in the soil of this gallery forest. The presence of viable spores in the soil after six months drought and in deeper soil layers shows the existence of a persistent soil spore bank in the gallery forest of the Panga Stream.
Acrostichum aureum and A. danaeifolium are morphologically similar sympatric species which grow in mangrove communities. To evaluate the cytological differences between these species, their karyotypes were analyzed with conventional staining, triple-staining with chromomycin A3 (CMA), distamycin A (DA) and DAPI, silver nitrate, and in situ hybridization with 45S rDNA as probe. Both species have the same chromosome number (2n = 60) with only small differences in chromosome size and morphology. The CMA banding pattern revealed four terminal bands in A. danaeifolium and six in A. aureum. DAPI bands were not found. The maximum number of nucleoli per interphase nucleus and the number of 45S rDNA sites were consistent with the number of CMA bands: four in A. danaeifolium and six in A. aureum. All meiotically analyzed materials showed 30II with normal chromosome pairing and segregation, except in one plant with a chromosome bridge and fragment in cells of anaphase I and II. It is suggested that sympatry and karyotypic orthoselection have contributed to keep the morphological and karyological similarities in such widespread species.
Isoetes savatieri has traditionally been interpreted as being a uniform aquatic ranging from the southernmost regions of South America to the central Andes of Chile and Argentina. An examination of herbarium material supports the recognition of two taxa, a southern I. savatieri and a more northern I. chubutiana, from central Chile and Argentina. The latter taxon is hexaploid and described here as a new species. The morphology of these species suggest that they are sister species resulting from divergence following a polyploidy event. These species, and several other species pairs, provide the best and, to date, only examples of allopatric divergence in polyploid Isoetes.
With most species of the Ophioglossaceae, gametophyte development and maturation are slow and some species have perennial gametophytes. A few species, including O. crotalophoroides, appear to have gametophytes that mature rapidly. To determine how fast the gametophytes of this species mature, they were grown in axenic culture. The early sequence of cell divisions following germination is the same as for other species of the Ophioglossaceae. The formation of mucilage on the proximal cell of the young gametophyte and on the rhizoids of older gametophytes has also been reported for other members of the family. The spores of O. crotalophoroides have the second fastest germination, 8 days, for this family. Gametophytes of this species grow faster than gametophytes of two Botrychium species. The gametangia form on smaller gametophytes of O. crotalophoroides than on those of Botrychium. Rapid spore germination, rapid gametophyte growth, and smaller gametophyte size at maturity all contribute to the formation of sexually mature gametophytes in 6.5 months. This is the fastest gametophyte maturation reported for the family.
The new species Hypolepis rubiginopilosula and Polypodium chirripoense are described, the new combinations Blechnum loxense var. stenophyllum, B. l'herminieri subsp. lehmannii, Diplazium ribae, Lastreopsis squamifera, Lomariopsissalicifolia, Pteridium caudatum subsp. arachnoideum, and Tectaria ×micheleriana are made, and three lectotypes are chosen for tropical American ferns.