Botanica Lithuanica, Volume 14, Number 3

2008 m.

Riparian zones provide suitable habitats for spreading of non-native plant species, simultaneously serving as migration pathways. At the same time, non-native invasions indicate the increasing anthropogenic pressure and make up a significant part of today’s changing biota. This paper presents a study of distribution of six alien species (Aster salignus, Petasites hybridus, Helianthus tuberosus, Impatiens glandulifera, Echinocystis lobata and Heracleum sosnowskyi) in Latvia. All species are known as non-native invaders of riparian habitats, such as riparian shrubs, floodplain meadows, tall herb nitrophilous communities on the riversides and wet slopes of valleys. Distribution data are based on the recent data gathered in field surveys and herbarium records as well as literature references. Maps of the current distribution, habitat preferences of all studied species and their spreading dynamics over the last century are presented.

Keywords: invasive, non-native, alien, riparian habitats, distribution, Latvia.

New locality of Asplenium ruta-muraria in 2008 was recorded in Švėkšna village (Šilutė district, West Lithuania). Over 40 individuals were found in cracks of an old stone fence. Though all Asplenium species are protected in Lithuania, their native status in the country is not certain. It is concluded that A. trichomanes is native at least in one locality. A. ruta-muraria and A. viride should be ascribed to the group of cryptogenic species, i.e. species that are not demonstrably native or alien.

Keywords: Asplenium ruta-muraria, Lithuania, habitat, distribution, status.

Cytogenetic effects of uranium on meristematic cells of the root tips of Vicia faba L. have been investigated. Seeds of the plant were kept in uranium standard for different time period (0.5, 1, 2, 5, 10 and 24 hours). The seeds treated with uranium were made sprout and the root tips obtained were prepared for microscopic examination. At the end of the microscopic examinations, some abnormalities such as chromosome breakings, untidily dispersion of the chromosomes, chromosome adherence were observed. Abnormalities were detected at each treatment depended on the time periods. Variety and number of abnormalities were usually seen to be increasing, depending on the increase of the treatment time. The obtained results were evaluated statistically.

Keywords: abnormalities, chromosome, uranium, Vicia faba.

Cyanobacteria were investigated in the epiphyton of five Lithuanian lakes. From totally recorded 84 Cyanophyceae species and varieties, 39 species belong to Chroococcales. Seven chroococcalean species – cf. Cyanobium parvum, Aphanothece elabens, Aphanocapsa parasitica, Chlorogloea rivularis, Hydrococcus cesatii, Chamaesiphon minutus, Geitleribactron periphyticum – represent a new contribution to the Lithuanian algaeflora. Species descriptions with original measurements and drawings, their occurrence, ecological and distribution data are provided. Four newly recorded cyanobacteria – Aphanothece elabens, Aphanocapsa parasitica, Chamaesiphon minutus, Hydrococcus cesatii – are widespread; cf. Cyanobium parvum, Chlorogloea rivularis, Geitleribactron periphyticum – rare. Chlorogloea rivularis preferred the laminae of Nuphar luteum; Geitleribactron periphyticum – stems of Phragmites australis. The latter algae species as well as cf. Cyanobium parvum dominated in the epiphyton of two investigated lakes (Duobulis, Gulbinas).

Keywords: new species, Chroococcales, cyanobacteria, epiphyton, lakes, Lithuania.

Red algae Audouinella hermanii is reported for the first time in Lithuania. A new locality and habitat of red algae Chroodactylon ornatum in freshwaters are also reported. Species morphological descriptions, illustrations, and world distribution data are presented.

Keywords: freshwater, Audouinella hermanii, Chroodactylon ornatum, Lithuania.

Forty-three species of non-poroid resupinate homobasidiomycetes were found on living above-ground wooden structures of trees and shrubs in Belarus. The specific sites for basidiomata attachment on host were classified, taking into account the preferences of different species. Thirty kinds of sites, or microhabitats, were distinguished. The most species-rich microhabitat, where 21 species were recorded, was non-injured bark of living trunks from ground level up to 2.5 m. Five species, typically inhabiting fallen wood and litter, occurred only at trunk bases. The second most preferable site was living bark, surrounding open wounds, colonized by 18 species, most frequent being Hyphodontia sambuci. Two species, Chondrostereum purpureum and Stereum hirsutum, manifested clear pathogenic abilities, causing the total death of tree or shrub.

Keywords: Chondrostereum, Corticiaceae s. l., Dendrothele, parasite, Peniophora, rhytidome, Stereum, wound.

Tobacco rattle virus (TRV) was identified and isolated from Cymbidium hybridum and Phalaenopsis sp. grown in Lithuania. TRV was found infecting orchids in mixed infection with Odontoglossum ringspot virus (ORSV) and Cymbidium mosaic virus (CymMV). Viruses have been identified by the mechanical inoculation of differential host plants, electron microscopy and DAS-ELISA. TRV identification was confirmed in RT-PCR. ORSV was identified in all examined orchid plants grown under greenhouse conditions in Ukraine. CymMV mixed infection with ORSV was found in three plants. The survey of orchid genera (20 species) growing naturally in Ukraine revealed the presence of Arabis mosaic virus (ArMV), TRV and Tomato aspermy virus (TAV). The most sensitive to viral infection were plants of Listera ovata, Neotia nidus-avis and Orchis purpurea species.

Keywords: Orchids, viruses, identification.