Botanica Lithuanica, Volume 4, Number 1

1998 m.

The genus Mentha L. is very complex taxonomically. The complexity is due to polymorphism, natural hybridization and phenotypic variation within the genus. Identification to interspecific level of most of natural mints is an insurmountable task even for experts. In the present paper an attempt was made to put the description, classification and identification of taxonomic groups of mints on a rigorous logical basis. Numerical taxonomical research of 127 local and 35 natural varieties of mints and garden escapes, introduced from various European countries, as well as 13 cultivars from the Ukraine and Russia was carried out at Kaunas Botanical Gardens in 1980–1990. The lists of descriptors and general diagnostical characters for Mentha taxa were presented. The mints to be preliminary classified were examined for limited number (7) of morphological character complexes. In description of mints, at least 34 qualitative (binary) and 6 quantitative morphological parameters were used.

Keywords: Mentha, numerical taxonomy, mathematical logics, theory of probability.

This paper continues publication of the conspectus of alien plant species recorded in Lithuania. The Solanaceae family in Lithuania is represented by 18, Boraginaceae by 8, Convolvulaceae by 3 species and the rest three families (Polemoniaceae, Cuscutaceae and Hydrophyllaceae) by one alien plant species each. Data on the first record, distribution, habitats, level of naturalization, means of immigration and biology (time of flowering, fructification and reproduction) of each species are presented. Five here described alien species are naturalized, 20 are casuals and naturalization level of 7 species in Lithuania is uncertain. Distribution of 2 species is mapped. Three species are excluded from the list of alien plant species.

Keywords: alien plant species, conspectus, Boraginaceae, Concolvulaceae, Cuscutaceae, Hydrophyllaceae, Polemoniaceae, Solanaceae, distribution, naturalization, reproduction, Lithuania.

The paper represents first data on liverworts in the Grazute Regional Park. In the course of short field period 33 species and 1 variety of liverworts belonging to 21 genera and 15 families were recorded in the park. Lepidozia pearsonii and Cephalozia bicuspidata var. lammersiana were reported for the first time in Lithuania. Species composition and distribution within the area as well as their frequency and abundance are briefly analyzed. Data on reproduction for liverworts of each collected specimen are provided.

Keywords: liverworts, flora, Regional Park, Lithuania.

Results of investigations on broad-leaved forest communities in Akmena river valley (Pagramantis Regional Park, south-west of Lithuania) are presented in this paper. The communities belong to the Tilio-Carpinetum betuli Traczyk 1962 association (Cl. Querco-Fagetea Br.-Bl. et Vlieger in Vlieger 1937). Floristic composition, structure and habitats of these communities are described.

Keywords: forest, vegetation, Tilio-Carpinetum betuli, the Akmena river valley, Lithuania.

Qualitative and quantitative aspects of the phytoplankton of the river Šešupė were studied in 1991, at a point 272 km from the source. Totally 69 taxa of phytoplankton were identified. The members of Bacillariophyceae and Chlorophyceae were dominating, representing respectively 69 % and 18 % of total species number. Cyanophyceae were represented only by a few species (7 % of total species number), but were abundant in cell number. Total cell abundance varied from less than 90 000 cells l-1 to more than 1 200 000 cells l-1. Phytoplankton development dynamics could be described as seasonal changes of three dominating groups of algae – diatoms, blue-green and green algae. Water discharge, temperature and light conditions seem to be the main controlling factors of phytoplankton dynamics.

Keywords: phytoplankton, species composition, abundance, seasonal dynamics, the Sesupe river, Lithuania

The microalgae algotest, one of the biotests, was used to evaluate the eutrophication changes in water basins. In 1986–1996 the investigations on trophic potential of Lake Dr?k?iai, channels and incoming streams were carried out using algotest Scenedesmus brasiliensis Bohl. A small amount of algotest biomass (4,0–22,0 mg/l) during 1987–1989 indicated Lake Dr?k?iai as water basin of low trophic potential. The trophic potential of Lake Dr?k?iai water began to increase since 1990. During 1993–1996 the biomass of algotest S. brasiliensis (annual average 25–50 mg/l) grown up in the water samples from the lake characterizes it as an eutrophicated water basin. The greatest biomass of algotest S. brasiliensis was mostly in the south-western part of the lake, which is under the influence of Visaginas town sewage water. In the water of this area the annual average biomass of algotest S. brasiliensis during 1986–1997 was 32,6 mg/l, meanwhile in other investigated areas of the lake it fluctuated from 24,7 to 26,3 mg/l.

Keywords: algotest, trophic potential, lake Druksiai, Lithuania.

The scientometrics or analysis of quantitative data is one of approaches to characterise the scientific activity in the past. Thus, it can be applied in the studies on the history of botany in Lithuania in 1919–1943. The scientific publications of that period provide with the quantitative data. Basing on them the quantitative parameters and indexes are drawn. The following quantitative parameters are presented and discussed: number of publications, number of their authors, number of publications written by scientific workers and index of scientific work output. The material concerns the fields of botany such as plant anatomy, plant physiology, floristics, phytosociology, plant taxonomy and phylogeny. The research work was carried out by the botanists of Vytautas Magnus University (VMU) (1922–1940), Vilnius University (VU) (1940–1943), Academy of Agriculture (AA) (1924–1943), Stephan Bator University (SBU) (1919–1939).

Keywords: botany, Lithuania, scientific publications, quantitative data.

Valdensia heterodoxa is described as the new species of Hyphomycetes to Lithuania. It is not rare, in some places common and abundant on leaves of Vaccinium myrtillus and Convallaria majalis.

Keywords: Hyphomycetes, Valdensia heterodoxa, distribution, Lithuania.