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The investigations were carried out in the southern part of the Czeszewo Forest located in Central Wielkopolska. The vascular flora of this area comprises 554 taxa, including 6 species rare for Poland, 29 rare for Wielkopolska and 14 protected by law. Noteworthy among forest species are the commonly recorded Arctium nemorosum, Cardamine impatiens, Cerastium macrocarpum, Galium odoratum, Stellaria neglecta, and the rare Actea spicata, Asarum europaeum, Bromus benekenii and Neottia nidus-avis. In the periodically flooded northern part of the Czeszewo Forest and by the Warta river, several species associated only with river valleys were found: Achillea salicifolia, Barbarea stricta, Gratiola officinalis, Pulicaria vulgaris, Scutellaria hastifolia, Senecio paludosus, Silene tatarica and Veronica longifolia.
Results of anatomical studies on the developing endocarps of Cornus mas and C. officinalis are presented. Formation of an endocarp and anatomical changes in its structure from the flowering stage to fully developed fruits were observed with the use of LM and SEM. In the process of anatomical development of endocarps the formation of two layers, i.e. the inner and the outer endocarp, was observed. Changes in their anatomical structure consisted in a gradual thickening of cell walls and their lignification. The lignification of endocarp cell walls begins in the inner endocarp, it proceeds in the outside parts of the outer endocarp, with an exception of several layers of cells forming the transition zone (circular strand) present on its margin, and finally, almost at the same time, in the rest of the outer endocarp. Cell walls of the cells distinguishing the germinating valves undergo thickening delayed by several days in comparison to other endocarp cells. Thickening of their cell walls starts in cells situated close to the inner endocarp and proceeds to its outer parts, and their lignification is not very intensive. The described scheme of the development and lignification of C. mas and C. officinalis endocarps is similar to that of Prunus cerasus (Rosaceae).
Micromorphological features of glumes, lemmas and paleas were examined under light and scanning electron microscopes in amphiploids of Aegilops geniculata, Ae. peregrina × Secale cereale and their parental species. The principal features include the size and shape of silica bodies, crown cells, prickles, macrohairs, stomata and the morphology of long cells. The SEM observations of glumes separate two parental forms of Aegilops by the type of prickles and types of wax on palea surface. The abaxial surfaces of lemmas in the parental species and amphiploids show the most taxonomical features. Amphiploids in many features exhibit an extended range of variation in comparison to their parental species, particularly in stomatal length. Epidermal features in amphiploids are inherited after Ae. geniculata and Ae. peregrina. Results of this study provided data on new quantitative and qualitative traits of the glumes, lemmas and paleas in the studied taxa.
The paper presents in the first time the results of a micromorphological study on stamens of Sansevieria species. Flowers of 15 species obtained from herbarium specimens deposited at the Royal Botanic Gardens, Kew, the Botanical Garden Berlin-Dahlem and the Botanical Garden in Poznań were studied. Observations were conducted under a light and a scanning electron microscope. The study revealed significant differences between the outer and inner surfaces of anthers. All species have a well-defined endothecium of enlarged cells with a U-shaped or helical secondary wall thickening. The article includes descriptions and illustrations of several quantitative and qualitative features of anthers and filaments of some Sansevieria species. Our study indicates that stamen micromorphology may be taxonomically significant.
The paper reports the information on distribution, habitats, and abundance of the rare, in the Wielkopolska, species Isopyrum thalictroides. In particular, characteristics of the abiotic habitats, phytocenoses are given, together with the data on abundance and structure of populations, production of flowers, fruit and seeds.
A revision of the Isopyrum thalictroides localities known from literature has been made. Exact position of the localities, the size of the forest community in which the species was found and its local name were established. The taxonomic classification of all herbarial specimens collected at the localities studied was tested.
The paper presents the results of a study on mericarps and seed morphology of four taxa occurring in Poland: Heracleum sphondylium subsp. sphondylium and subsp. sibiricum, H. mantegazzianum and H. sosnowskyi. Apart from selected biometric traits we analysed pericarps and seed-coat patterns using a stereoscopic microscope (SM) and a scanning microscope (SEM). Considerable diff erences in the dorsal surface of mericarps were observed, but major structural similarities were found on the ventral surface of mericarps. Pericarp surface diff ers signifi cantly between native and alien taxa in terms of secondary sculpture. The examined seeds were characterised by reticulate primary sculpture with diff erent size and shape of testa cells. The macro- and micromorphological characteristics of the mericarp and seeds may provide valuable additional diagnostic criteria for delimitation of Heracleum and can be used in the identifi cation of fruits and seeds.
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