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Dennstaedtiaceae is a monophyletic, extant family of ferns with sub-cosmopolitan distribution and ca. 265 species. Rhizome morphology in the Dennstaedtiaceae is relatively well known, yet its anatomy has been poorly explored. We performed morpho-anatomical studies on 26 taxa from eight genera, mostly from Brazil, Japan, and New Zealand. Among the studied species, the main rhizome type is long-creeping with alternate phyllotaxy and a solenostele s. str. The exception is Blotiella lindeniana, which has ascending rhizomes with radial phyllotaxy and a dictyostele. A polycyclic solenostele was found in Dennstaedtia (“Patania”) cornuta, D. (“Patania”) dissecta, and two subspecies of Pteridium arachnoideum. Lateral-line aerenchyma characterized Blotiella lindeniana, Histiopteris incisa, Hypolepis spp., Paesia spp., and Pteridium arachnoideum subspp. The position of sclerified parenchyma in the cortex and pith varied among species. Our data enabled us to hypothesize evolutionary patterns of rhizome evolution in extant lineages of the Dennstaedtiaceae. The “Monachosorideae” has retained ancestral conditions: short-creeping to ascending rhizomes with dictyostele s. str. In the “Hypolepidoideae”, two notable changes occurred in Blotiella and Pteridium (in which the solenostele evolved into a polycyclic solenostele). In the “Dennstaedtioideae”, one notable change occurred in Dennstaedtia (“Patania”), namely parallel evolution with Pteridium (in which the polycyclic solenostele has also evolved). We present illustrations, morpho-anatomical descriptions, evolutionary inferences based on the available phylogeny, and supporting tools for studying the taxonomy, systematics, phylogeny, and paleontology of the group.
Oogenesis of Lygodium japonicum (Thunb.) Sw. is studied using TEM and cytochemical techniques. The early development of the archegonia of L. japonicum is similar to those of the core-leptosporangiate ferns. A mature archegonium always contains an egg, a ventral canal cell (VCC) and a binuclear neck canal cell (NCC). With the development of the egg, a separation cavity forms between the egg and the VCC. However, a pore region, with a diameter of about 3.5 μm, constantly connects the egg and the VCC. The canal cells degenerate gradually accompanied by the accumulation of mucilaginous secretions around the canal cells. PAS reaction reveals that these secretions are polysaccharide in nature. Later development of the archegonia of L. japonicum differs greatly from the core-leptosporangiate ferns. The egg nucleus becomes highly irregular and two types of nuclear evaginations are formed during oogenesis. When the egg matures, no egg envelope or fertilization pore are formed. Only a layer of amorphous material is deposited on the outer surface of the egg. This is the first observation of a fern species that has a pore region but does not result in the formation of a fertilization pore. The pore region appears to determine the formation of the fertilization pore. These observations are consistent with the hypothesized phylogenetic position of L. japonicum relative to the core leptosporangiate ferns.
The presence of a nutritionally independent gametophyte generation of spore-producing land plants, including those of ferns, has often been cited as an important factor in explaining their broader geographic distribution at the level of species and genera relative to that of seed plants. Dispersing spores widely and successfully is critical to establishing populations–both in terms of production and dispersal distance–yet literature with direct observation of these variables is scant. We double the number of studies directly observing dispersal in fern species by conducting spore trap experiments on Adiantum pedatum and Deparia acrostichoides, which grow together at a site in southeastern Ohio, U. S. A. In interpreting these results, we summarize the literature on spore production in ferns and examine the contribution of phylogenetic history to the variation in spore production across ferns. We corroborate findings that the vast majority of spores produced are dispersed within 2 m of the parent plant. Additionally, spore production in ferns varies widely between species but shows some phylogenetic conservatism and is correlated to frond area. We conclude that gametophyte (and sporophyte) establishment over distances greater than 3 m is governed by rare spore dispersal, but the sheer number of spores produced increases the probability of this event occurring and the establishment of sporophytes is likely dependent upon gametophytic traits. In ferns as a whole, differences in spore production are related to differences in frond area, but may also be related to overcoming genetic complications involved in long-distance dispersal.
On the basis of field and herbarium work, 11 species of Cyathea from Peru are described as new. Cyathea angelica, C. hierbabuena, C. pibyae, C. recondita, C. xerica, and C. yambrasensis come from the headwaters of the Marañón river in northern Peru, and C. estevesorum, C. lehnertii, C. monteagudoi, C. rocioae, and C. valliciergoana from the eastern flanks of the Andes of central to southern Peru. Most of the new species described occur in sandstone soils and may be restricted to it. They are illustrated and discussed regarding their biogeography and possible phylogenetic affinities.