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Does a gender of Welwitschia mirabilis plants influence their photosynthetic activity?
Welwitschia mirabilisHook.f. (Welwitschiaceae, Gnetales) is a gymnosperm plant unique in its habit with an isolated taxonomic position. This species is dioecious, but no studies of its photosynthetic activity were conducted with examination of differences among male and female plants. To fill this gap, the day and night photosynthetic activity of male and female specimens ofWelwitschia mirabiliscultivated in the botanical garden was studied in controlled conditions. Photosynthetic activity was studied using net photosynthetic rate (PN), stomatal conductance (gs) and intercellular CO2concentration (Ci) parameters. Additionally, a normalized difference vegetation index (NDVI) was used to assess the condition among male and female plants in full sunlight. The studiedWelwitschiaplants revealed variability in photosynthetic activity both during the day and the night. The photosynthetic activity was low in the morning hours and higher in the afternoon. There is a difference in the photosynthetic activity during the night between sexes, being higher in female specimens. Stomatal density was evaluated separately for adaxial and abaxial leaf surfaces. Statistically significant differences in the stomatal density on abaxial and adaxial leaf surfaces were observed in both sexes, especially distinctive in female specimens. NDVI has revealed that there were weak differences between male and female plants.
Micromorphology of fern spores as a tool in taxonomy of East-Central European species from the family Aspleniaceae (Polypodiopsida)
The family Aspleniaceae consists of ca. 730 fern species found primarily in the tropics but present also in the temperate zone. Recently, researchers have been increasingly interested in spore morphology, as it provides valuable information used in taxonomic and phylogenetic analyses. This study aimed to (1) describe in detail spore morphology in species of the family Aspleniaceae from Central and Eastern Europe; (2) attempt to use their features in taxonomic analyses; and (3) create a key to species identification on the basis of spores. e study was based on <i>Asplenium</i> spores of 10 species from 57 localities. The morphological type of spores was very similar in all the studied species, whereas spore microsculpture varied widely between and within species. This makes it difficult to use spores for species identification. Nevertheless, spore morphology allows the identification of six species, while the others form groups composed of 2–3 species each. In the group consisting of <i>A. adulterinum</i>, <i>A. trichomanes</i>, and <i>A. ruta-muraria</i>, the last species is distinguished by larger spore size (more than 50 μm long).