Šilagėlės genties augalai yra nepaprastai gražūs, dekoratyvūs ir puošnūs, bet kai kurios šilagėlių rūšys sparčiai nyksta, todėl yra saugomos įvairių teisės aktų pagalba. Lietuvoje augančios pievinė (Pulsatilla pratensis) ir vėjalandė šilagėlės (P. patens) savo paplitimo arealuose yra nykstantys augalai. Vėjalandė šilagėlė dėl spartaus nykimo Europos mastu, visose šalyse kuriose ji paplitusi, yra įrašyta į saugomų rūšių sąrašus ir juose dažniausiai priskiriama prie išnykstančių ar pažeidžiamų rūšių kategorijų. Pievinė šilagėlė nėra taip sparčiai nykstantis augalas, todėl Europoje yra priskiriama endeminėms rūšims (PILT, KUKK, 2002). Siekiant parengti geras rekomendacijas šilagėlių apsaugai, kurios jas įgyvendinus duos teigiamus rezultatus, pirmiausia yra būtina surinkti visus įmanomus duomenis apie šią rūšį. / The genus Pulsatilla includes perennial plants of the Ranunculaceae family. In Lithuania this genus is represented by two species and one hybrid: P. patens, P. pratensis and P. ×wolfgangiana. P. patens is endangered throughout Europe and is included into the Red Data Books of almost all European countries. Endemic species of Europe P. pratensis is included into the Red Data book just in several European countries. P. ×wolfgangiana is very rare hybrid species, occurring in areas where both parental species occur together. The aim of this work was to estimate composition and state of populations of the genus Pulsatilla in Lithuania. The tasks of the work are as follows: 1) to reveal plant communities in which members the genus Pulsatilla grow; 2) to evaluate structure of populations according to stages of plant maturity; 3) to investigate density of P. patens and P. pratensis individuals in populations; 4) to compare variation of Pulsatilla morphological characters and their dependence on habitat conditions; 5) to evaluate optimum habitat conditions for Pulsatilla populations in Lithuania. Results of the research enable to reveal composition and state of populations of the genus Pulsatilla in Lithuania and to prepare recommendations for management of their habitats.

This thesis deals with interspecific hybridization in sympatric populations of Pulsatilla patens and P. pratensis. The key aim was to assess karyological and phenotypic variation in the study group. DNA flow cytometry revealed three non-overlapping groups of genome sizes, corresponding to P. patens, P. × hackelii and P. pratensis. The frequency of interspecific hybridization was low, accounting to approx. 3% of analyzed plants. Morphometric analyses identified a set a reliable species-specific characters, including number of divisions the leaf, length of petiole the part of leaf, number of smaller parts of leaf and colour of blossom. Although the majority of hybrid individuals flowered and set fruits, their fertility was reduced considerably. The threat from interspecific hybridization to parental species is therefore rather low.

The purpose of this thesis was to study interactions between systemic fungal diseases and perennial plants. Using the systemic rust Puccinia minussensis on the host plant Lactuca sibirica, and the rust Puccinia pulsatillae on the host plant Pulsatilla pratensis, this thesis focused on: (i) the effects of systemic diseases on their hosts (ii) host and pathogen responses to abiotic factors, (iii) the importance of life history strategies for understanding host-pathogen interactions, and (iv) the evolutionary consequences of living in close associations. Results of greenhouse experiments showed that Lactuca sibirica had a high plasticity in growth, since it produced significantly more shoots in favourable than in unfavourable growth conditions. Both the disease levels and the number of healthy shoots (i.e. escape) were significantly higher under favourable conditions. Disease spread within the rhizome was found to be incomplete, and the risk of aecidial- infection decreased with distance from the parent. Furthermore, one isolate of the fungus had highest success and reduced the host plant biomass and shoot production more on the clone it was collected on compared to four other clones . In the field, disease levels were found to fluctuate more at localities subjected to disturbance, the host and pathogen abundances were found to be in phase and the pathogen showed no delayed response to increasing host densities. The rust Puccinia pulsatillae on Pulsatilla pratensis showed no fluctuations between years, low infection rates, and disease levels were higher in ungrazed compared to grazed sites. There was no escape from the disease in this system. A comparison of characteristics of different systemic fungi and hosts with different growth patterns indicated that the life history strategies of both host plants and pathogens need to be studied if the long-term consequences of host-pathogen interactions are to be predicted. / <p>Diss. (sammanfattning) Umeå : Umeå universitet, 1993, härtill 5 uppsatser.</p> / digitalisering@umu