Vegetation analyses (phytosociological relevés) of 20 peat bogs arranged along an altitudinal gradient in the southern part of the Czech Republic, Central Europe, revealed relationships between vegetation and environmental gradients. Six of the peat bogs were investigated in detail. The bogs were dominated by Pinus rotundata, a species endemic to Central Europe, and its hybridogenous populations with P. mugo (the hybrid is called P. ×pseudopumilio), with increasing proportions of the latter at higher altitudes. Data were processed using indirect (DCA) and direct (CCA) gradient analyses. Environmental variables (depth of the water table, mean and minimum temperatures, precipitation, pH, conductivity, NH4 and PO4 concentrations, total P, but not total N nor NO3 concentration), as well as biotic characteristics of the sites, such as species composition, and growth form of the dominant pines, were closely correlated with altitude. Woody species, herbs and bryophytes responded to the altitude similarly. Results also indicated the unique characteristics of each bog.
The Melampyrum sylvaticum group is a complex of three closely related species. This group is most variable in the Carpathian region. Interactions among different levels (within-population to interspecific) of genetic variation and influence of the environment are considered to be the main sources of the complicated morphological variation in this region. Morphological variation in the M. sylvaticum group was studied in mountain ranges of the Hercynian Massif and in the Western and Ukrainian Carpathians. Several populations were sampled at different altitudes within each mountain range. Hierarchical partitioning of morphological variation at different levels (within populations, among populations within a mountain range and among mountain ranges) was calculated. Correlations among groups of morphological characters and altitude were calculated. The largest proportion of variation on a large geographic scale (i.e. among mountain ranges) was detected in anther length and several corolla characters (length of the lower corolla lip, height of upper corolla lip), whereas these traits were homogeneous at a local scale (within populations and among populations in one mountain range). An opposite pattern (i. e. high proportion of variation at the low levels, which blurred possible large scale differences) was found in bract traits and several calyx characters. Moreover, a strong correlation between bract length and altitude was observed. The observed changes in the proportions of morphological variation and response to altitude suggest a close connection between bract characters and environmental factors (or lower levels of genetic variation). On the other hand, some of the flower characters seem to be genetically determined and thus might reflect evolutionary processes (early diversification, potential hybridization, introgression) on which the taxonomic treatment of the group should be based. The most distinct differences were detected between samples from the Ukraine and south-western part of Bohemia. Populations from the the Sudeten Mts and the Western Carpathians were variable and morphologically intermediate, forming a continuum between the two extremes.
A detailed cytogeographic and morphometric study of the Asplenium trichomanes group in the Czech Republic is presented. We detected diploid (2n = 72), tetraploid (2n = 144) and hybrid triploid plants (2n = 108). Based on the morphometric study, four intraspecific taxa are recognized. These taxa correspond to the four subspecies of A. trichomanes (A. t.subsp. trichomanes, <I.A. t. subsp. quadrivalens, A. t. subsp. pachyrachis and A. t. subsp. hastatum) distinguished in the floras of western, southern and northern Europe. Triploid plants were determined as A. t. nothosubsp. lusaticum (A. t. subsp. trichomanes × A. t. subsp. quadrivalens). The individual morphological characters used for determining subspecies are evaluated and a determination key presented.
Parazitické rostliny představují velmi specifickou skupinu v rámci rostlinné říše, jejíž zástupci jsou jinak autotrofní. V průběhu evoluce vynalezly tyto rostliny mnoho způsobů parazitismu na zdrojích, strukturách a službách, ve kterých využívají jiných rostlin, hub nebo dokonce živočichů. V článku jsou definovány jednotlivé funkční skupiny parazitických rostlin a stručně popsána jejich biologie. and Parasitic plants present a very specific group among otherwise autotrophic representatives of the plant kingdom. During evolution, these plants invented different ways of parasitism on resources, structures and services, exploiting other plants, fungi and even animals. Individual functional groups of parasitic plants together with their biology are described in the article.
Over the last decade there has been a tremendous increase in the use of flow cytometry (FCM) in studies on the biosystematics, ecology and population biology of vascular plants. Most studies, however, address questions related to differences in genome copy number, while the value of FCM for studying homoploid plant groups has long been underestimated. This review summarizes recent advances in taxonomic and ecological research on homoploid plants that were made using FCM. A fairly constant amount of nuclear DNA within each evolutionary entity together with the often large differences between species means that genome size is a useful character for taxonomic decision-making. Regardless of the number of chromosomes, genome size can be used to delimit taxa at various taxonomic levels, resolve complex low-level taxonomies, assess the frequency of interspecific hybridization or infer evolutionary relationships in homoploid plant groups. In plant ecology and evolutionary biology, variation in genome size has been used for prediction purposes because genome size is associated with several phenotypic, physiological and/or ecological characteristics. It is likely that in the future the use ofFCM in studies on taxonomy, ecology and population biology of homoploid plants will increase both in scope and frequency. Flow cytometry alone, but especially in combination with other molecular and phenotypic approaches, promises advances in our understanding of the functional significance of variation in genome size in homoploid plants.