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Glyphosate, a systemic herbicide, is used against weeds in agricultural fields as well as against invasive plants in pastures, forest plantations, and urban environments. Its frequent and widespread use can negatively impact the surrounding natural non-target vegetation following the accidental drift of spray droplets, leaching, or persistence as residues in the soil. Because ferns possess a life cycle with independent sporophytic and gametophytic generations, herbicides may cause a different impact on each life stage. The objective of the present study was to evaluate the effect of four concentrations of glyphosate (0.33, 0.65, 2.72, and 10.89 g active ingredient L-1) and water as control treatments on spores, gametophytes, and two sporophyte size classes of one native (Blechnum appendiculatum Willd.) and two introduced fern species in Mexico (Macrothelypteris torresiana (Gaudich.) Ching and Thelypteris dentata (Forssk.) E.P. St.John). Spore germination was evaluated 10 days after herbicide treatment and the percentage of remaining green tissue was measured at 7, 30, and 90 days after herbicide treatment. Plant survival was determined at the end of the experiment. Glyphosate suppressed spore germination nearly completely and increased tissue discoloration of all green life stages at higher concentrations and after longer time intervals. After 7 and 30 days, small sporophytes of all three species were significantly more discolored than gametophytes and large sporophytes at concentrations ≤ 0.65 g a.i. L-1, although after 90 days differences among life stages were no longer significant, and no life stage survived at concentrations ≥ 2.72 g a.i. L-1. At the lowest concentration (0.33 g a.i. L-1), however, 50–69% of the plants of all three species and life stages survived after 90 days post-treatment. Macrothelypteris torresiana was significantly more tolerant to glyphosate than the other two species during the first 30 days after treatment, mainly because of its less damaged small sporophytes, perhaps due to a thicker waxy cuticle that may initially reduce herbicide absorption in this species. We conclude that even glyphosate concentrations of 0.33 g a.i. L-1 may negatively impact natural spore banks of ferns and result in mortality of 31–50% of all green life stages. Such negative effects may also eliminate at least the most susceptible fern species in habitats that are frequently exposed to such glyphosate concentrations.
All North American firmosses (Huperzia: Lycopodiaceae) produce highly specialized vegetative propagules known as gemmae. Though gemmae are of interest to morphologists, they have been used only rarely as aids in identification. To improve understanding of their variation among North American species and to explore their systematic utility we surveyed gemmae of all species in North America north of Mexico and provide measurements, comparative descriptions, and images. Several characters of the gemmae, including their size, shape, and morphology of the leaves that comprise them vary considerably across the species studied and can be used to distinguish species. A dichotomous key based on gemma characters is provided, and several notable range expansions are reported. We anticipate this study will help resolve confusion regarding the identity of North American Huperzia species, particularly among the taxa in the northern and western regions of the continent, which remain poorly understood.
Veracruz, with 542 recorded species, is the third richest state in Mexico in terms of total fern diversity. Field work, herbarium studies, and a revision of literature during the last decade revealed 22 new state records. Five of these belong to Elaphoglossum, four are filmy ferns, and three are grammitids. Most of the new taxa were collected in the endangered humid montane and pine-oak forests of the central and Los Tuxtlas area during recent research projects. Another 13 species, mainly within Elaphoglossum and Selaginella, have been published as new records in the literature. Whereas several of these might possibly be confirmed in the future, others form part of poorly known species complexes that require specific studies, and we consider them as doubtful or unverified. Our study highlights the need of more fern inventories in remote and mostly unexplored areas, as well as revisions of national and local herbaria, both of which may reveal additional species new to science or range extensions.
The results of phytosociological research conducted on the fern vegetation of rock crevices and clefts of the Pamir-Alai Mountains in Tajikistan are presented. During field surveys done in 2010–2013, 78 phytosociological relevés were sampled. Plant species were recorded according to the Braun-Blanquet cover-abundance scale. A synopsis of the fern communities of the montane and high altitude zones in Tajikistan is proposed. In the examined vegetation plots, species of 9 ferns, 58 angiosperms and 13 mosses were recorded. The most frequent ferns were: Cystopteris fragilis, Cheilanthes persica, Asplenium ruta-muraria, Asplenium ceterach, Adiantum capillus-veneris and Cryptogramma stelleri. Six plant associations could be distinguished: Cheilanthetum persicae, Cryptogrammetum stelleri, Soncho transcaspici-Adiantetum capilli-veneris, Asplenio-Ceterachetum officinarum, Asplenio-Cystopteridetum fragilis, and Asplenietum trichomano-rutae-murariae. The first three associations are described for the first time. The main factors determining the species composition of classified associations are elevation range, microhabitat humidity and moss cover. A minor role is played by the geographic distribution range and rock type.
The family Ophioglossaceae is one of the oldest fern lineages, characterized by a specific sporophyte structure where each leaf is divided into a fertile (sporophore) and a sterile (trophophore) segment. The aims of this study were to analyze: (1) the growth rate and duration for each developmental stage of the sporophyte of the protected fern Botrychium lunaria (L.) Sw., (2) the correlation between sporophore and trophophore size, and (3) the effects of soil conditions and density of other herbaceous plants on the development and number of individuals of B. lunaria to suggest some possible methods for its protection. Field research was conducted in a threatened population of this species in alluvial ash forest (Astrantio-Fraxinetum Oberd. 1953) at the base of Dziewicza Góra, a wooded hill in western Poland. During leaf emergence, the first and longest stage of development, the leaf developed intensively. Subsequently, its subdivision into the sporophore and trophophore became apparent. Throughout the four subsequent stages of sporophyte development (initial maturation, final maturation, spore release and senescence), the sizes of the trophophore and sporophore were significantly correlated. Additionally, sporophore size was affected by abiotic factors, including the total N and organic C contents of the soil. In patches with a higher cover of the herb layer we observed a smaller number of individuals of B. lunaria, so active protection by control of competing plant species seems necessary to ensure the survival of this population. Our results may help to design an effective conservation strategy for this rare and threatened fern in Poland and elsewhere.
Asplenium scolopendrium var. americanum is a federally-listed fern species that is found in several northern populations in the U.S. and Canada, as well as in three isolated locations in the southern U.S. In vitro methods were applied to the germination, propagation, and cryopreservation of this species. Germination of spores was obtained both in vitro and on soil, but the production of sporophytes from gametophytes did not begin until over two years after the spores were sown. In vitro cultures of both sporophytes and gametophytes were established, but sporophyte production from gametophytes has thus far only been observed on soil. Both in vitro-grown gametophytes and sporophytes survived cryopreservation using the encapsulation-dehydration procedure. Preculture on ABA-containing medium increased survival of sporophytes after cryopreservation, but good survival of gametophytes was observed with or without ABA. The use of Green Globular Body-like sporophyte tissue demonstrates the use of this tissue for fern cryopreservation. The success of these protocols demonstrates that in vitro methods can be applied to the propagation and preservation of A. scolopendrium var. americanum, and possibly other fern species with similar growth forms. Propagated plants could assist in restoration of the species and cryopreservation could be used to preserve germplasm of such propagated lines into the future.
The lycophyte genus Isoëtes L. is nearly cosmopolitan, with approximately 350 species, 23 of which occur in Brazil. The lack of adequate distinguishing morphological characters in the leaves and stems, as well as the frequent cases of hybridization and polyploidy, makes the identification of species very difficult. Usually the spores provide the best characters for distinguishing species within Isoëtes, but these can vary in size because of polyploidy and hybridization. In this work we studied the variation in size of both mega- and microspores, and the relationship between size and ploidy level. We also present the first chromosome counts for seven species that are endemic to Brazil: I. goebelii (2n = 33), I. martii (2n = 44), I. maxima (2n = 22), I. organensis (2n = 66), I. ramboi (2n = 44) I. smithii (2n = 44), and I. spannagelii (2n = 22). Our results suggest a correlation between ploidy level and spore size can be useful for the establishment of a preliminary hypothesis on polyploidy and hybridization among Brazilian Isoëtes.
Most morphological and floristic studies of lycophytes and monilophytes have been conducted in regions with humid and sub-humid climates, leaving dryer regions of the earth virtually unexplored. Arid and semi-arid zones make up about 50% of Mexico's land area; hence, the objectives of this study were (1) to undertake an inventory of fern and lycophyte species present in a region of central Mexico covered mainly by xerophilous vegetation (Valle del Mezquital, Hidalgo); and (2) to analyze patterns of morphological variation of the species found with respect to environmental conditions. Monilophytes and lycophytes were collected in all vegetation types identified within the study area along an elevation gradient between 1200 and 2800 m. For each species, growth substrate, life form and foliar strategy were recorded, and ten morphological characteristics were evaluated in order to determine their variation and correlation with elevation, rainfall, temperature and vegetation type. The data obtained were analyzed using univariate and multivariate techniques. Ten families, 25 genera and 72 species of monilophytes; and one family, one genus and eight species of lycophytes were identified. Quercus forest had the highest species richness of lycophytes and monilophytes followed by arid tropical scrub. The most common life forms by substrate were epipetric and terrestrial, the latter represented by chamaephytic, cryptophytic and hemicryptophytic life forms. Most species showed a xeromorphic foliar strategy, as a consequence of prevailing dry conditions. An analysis of morphological leaf characteristics of the species revealed patterns of variation and covariation, primarily related to vegetation type, which are linked to differences in temperature and moisture conditions along the studied elevation gradient. Monilophytes and lycophytes, like other groups of plants, have developed a set of morphological adaptations, which may function together or in various subsets and at different degrees of efficiency to enable plant species to cope with the environmental conditions in their habitats.
A neotype was chosen for Cheilanthes incisa by previous workers because there were apparently no extant syntypes. Recently, we found some extant isosyntypes in some European herbaria (L, LE, OXF, and PRC). Thus, we here select a lectotype for C. incisa, superseding the previous neotype. We also provide an updated synonymy.