The tree fern Alsophila setosa, occurs in primary and secondary forests of southern and southeastern Brazil. Two populations in secondary forest formations in the northeastern part of the State of Rio Grande do Sul, in the municipalities of Morro Reuter (45 plants) and Sapiranga (48 plants), were studied to estimate the ages of the plants. Two approaches were tested, one based on the total length in relation to the yearly growth rate of the caudex, and the second on the total number of scars and remains of stipe bases along the caudex in relation to the yearly frond production. Estimates based on growth rates and total length did not agree with the information and records of the past land use, whereas frond production over a longer time period presented acceptable estimates. The development of a new plant formed through vegetative reproduction was observed during three years. A brief discussion of the problems of age estimates in tree ferns is presented.

While compiling a plant inventory for a 20 acre forest fragment in Florida City, Miami-Dade County, Florida, on March 30, 2006, an unusual Thelypteris species was collected. The specimens did not correspond to any species reported from Florida (Wunderlin and Hansen, 2000). Using keys in Proctor (1989), Sánchez et al. (2006), and Morton (1963) it was tentatively identified as T. sancta (L.) Ching. A specimen was sent to Alan R. Smith, an expert on the genus, who confirmed this identification.

The development of gametophytes in Bolbitis bernoullii, B. portoricensis and B. umbrosa (Lomariopsidaceae) is described and compared. Spores are monolete, ellipsoid with prominent winged perispore. Germination is of the Vittaria type and the prothallial development is of the Drynaria type. Collenchyma-like thickenings at the corners of the wing cells were not observed. Adult gametophytes are cordate with scarce marginal hairs near the shallow notch. Gametangia are of the common type found in homosporous leptosporangiate ferns. Bolbitis portoricensis develops the first leaf of the sporophyte after 6 to 8 months, with polocytic stomata. In B. portoricensis, vegetative propagation is present in old thalli 6 to 8 months after cultivation.

A putative hybrid of unknown parentage was discovered in Walker County, Texas. Taxonomic features resemble both Thelypteris kunthii and Thelypteris ovata var. lindheimeri indicating hybridity. Spores of the putative hybrid examined by microscopy appeared malformed and were sterile with 0% germination. Guard cell measurements were intermediate to the presumed diploid and tetraploid parental species suggesting that the hybrid is triploid. Qualitative and quantitative phenetic characters examined were an array of parental and intermediate characters, suggesting that it had resulted from a cross between Thelypteris kunthii and Thelypteris ovata var. lindheimeri.