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The ligule morphology in three Indian species of the genus Selaginella, e.g., S. bryopteris, S. repanda and S. panchghaniana is described for the first time. Though the leaves (ventral and dorsal) in all the three species are typically normal, some dorsal leaves in S. panchghaniana have two ligules, bifid tips and lobed bases. The form of ligules is variable within each species but the overall shape (outline) is constant. The size of ligules may be influenced by environmental conditions. The presence of glandular cells at the margin of the tip of ligules indicates a water secreting function.
The anatomy of the foliar nectaries of four drynarioid species (Drynaria quercifolia, D. rigidula, Aglaomorpha coronans and A. acuminata) is described. The nectaries of all four species are vascularized modifications of the leaf blade and are distinct from surrounding tissue. They are composed of densely staining tissue with small isodiametric cells and reduced intercellular spaces. The nectaries of D. quercifolia and A. coronans occur as patches of tissue on the leaf blade. In contrast, the nectaries of D. rigidula and A. acuminata are stand-alone structures. The nectaries of A. acuminata represent the most specialized nectaries yet described among the ferns. The contribution of these data to cladistic analyses of Drynaria and Aglaomorpha is discussed.
Oogenesis in the fern Adiantum flabellulatum was studied using transmission electron microscopy. The newly formed egg is closely appressed to the archegonial jacket cells. Plasmodesmata connect the egg and the ventral canal cell, but are absent between the egg and the jacket cells. During maturation, a separation cavity forms around the egg. However, a pore region, persistently connecting the egg and the ventral canal cell, is reported for the first time. Subsequently, an osmiophilic egg envelope is formed, from a combination of the products of sheets of endoplamic reticulum and osmiophilic bodies in the egg cytoplasm. The absence of this envelope from the region where the egg and ventral canal cell were formerly interconnected produces a fertilization pore, which is believed to be an entrance for the sperm penetrating the egg. In the mid stages of egg maturation, the nucleus envelope produces extensive evaginations which then appear to be sequestered into the egg cytoplasm recalling a similar phenomenon in the eggs of other ferns. Degeneration of the neck canal cells is associated with the secretion of copious mucilaginous material.
The gametophytic generation of Polystichum pycnolepis (Dryopteridaceae), including spore germination, morphological development of the gametophytes, major vegetative features and sexual expression, was studied. Spore germination was of the Vittaria model and the developmental pattern was of the Aspidium model. Adult gametophytes were cordate and hairy, with unicellular hairs located in the margins and the surface of the prothalli. In addition, hairs of P. pycnolepis were papillate, secretory and the marginal ones septate. Gametangia were of the normal type described for leptosporangiate ferns. The gametophytes produced at first instance a high proportion of female gametophytes. Polystichum pycnolepis formed few bisexual gametophytes with scarce antheridia. No male gametophytes for this species were detected. Thus, the species seemed to be promoting intragametophytic selfing and, to a lesser extend, intergametophytic unions between bisexuals and females.
Ecology, syntaxonomy and population size of Gymnocarpium dryopteris have been studied, especially during the period 1979–1991 by collecting data on 419 colonies in the Kuinderbos (a planted woodland in the Noordoostpolder, a polder reclaimed from the former Zuiderzee in 1942) and 74 colonies elsewhere in the Netherlands. In this paper the Kuinderbos population is compared with other Dutch populations (pleistocene area) in order to provide more insights in the ecology of the species and circumstances facilitating high density. Populations in Germany were studied as reference. In the period 1979–1991 the species was recorded in the Netherlands with at least 670 colonies, of which 89% are in the Kuinderbos. Gymnocarpium dryopteris prefers shadowed ditches and drainage trenches, but can grow at various other habitats as well. Especially at the western and southern part of the Netherlands, the species grows on canal walls. Sites with Gymnocarpium dryopteris belong to different communities. In the Kuinderbos stands of Picea sitchensis are preferred, while elsewhere in the Netherlands the species prefers the Quercion roboris-petreae (Fago-Quercetum) or Pseudotsuga mensiezii-stands. Gymnocarpium dryopteris is accompanied by 14 fern species, at the Kuinderbos by 12 fern species, with Athyrium filix-femina as characteristic species, often indicating potential sites. Rhizomes are shallow creeping, at average 2.6 cm below the surface (0.5–8 cm). It grows in the ecto-organic layer or just below this layer. At trench sides it often grows in the mineral layer. Most colonies are within the influence of the watertable. The Dutch colonies are small and colonies with more than 1000 fronds are rare. This probably indicates that most colonies are less than 20 years old. Colonies with more than 100 fronds are often fertile, with less than 20% of the fronds bearing sori. At the wall habitat small-sized individuals may be fertile as well. The high density in the Kuinderbos can be attributed to an optimal water supply from a peat subsoil, the composition of the ecto-organic layer consisting of Picea needles and an optimal light climate. The high density in Picea sitchensis within the Kuinderbos is unprecedented in Europe and makes these stands resemble the natural habitat of Picea sitchensis at the west coast of N. America.
Root endophyte colonization was investigated in 32 fern and lycophyte species of 11 families collected from the Celaque National Park in Honduras. Arbuscular mycorrhizae (AM) were found in 11 plant species (34%) of Anemiaceae, Gleicheniaceae, Ophioglossaceae, Pteridaceae, Selaginellaceae, Thelypteridaceae, and Woodsiaceae. The abundance of arbuscular mycorrhizal fungi (AMF) in roots varied with particular species, ranging from 4% (Sticherus underwoodianus) to 78% (Thelypteris patens). The morphological AM colonization pattern of all investigated species was of the Paris-type. The mycelium of dark septate endophytes (DSE) was found in 19 species (58%), and was observed both in the roots of plants that were colonized by AMF and were devoid of AM association. However, in both cases the percentage of root colonization by these fungi was low. Exceptions were Asplenium serra, Elaphoglossum erinaceum, Lellingeria prionodes, and Lycopodium thyoides, where abundant DSE hyphae were observed. Our results are the first detailed report of both AMF and DSE associations of these plant species. Moreover, the mycorrhizal status of 27 plant species is reported for the first time.