Summary1. This study explores the importance of flower position for reproductive success of individual flowers of the deceptive terrestrial orchid, Dactylorhiza maculata (L.) Soó. 2. Upper flowers had smaller lips and produced lighter pollinia than those in other parts of the inflorescence, probably due to architectural effects. 3. Dry weight of seed capsules decreased from bottom to top in the inflorescence in both open-pollinated and hand-pollinated plants. However, removal of flowers from the middle and lowest parts of the inflorescence considerably increased seed production of the upper flowers. Decreased seed set was due to decreased resource availability because of the long maintenance time of opened but not pollinated lower flowers. 4. Experimental self-pollination resulted in reduced seed set compared to that following pollination with cross-pollen, but decreased seed set was independent of flower position within an inflorescence. 5. Dactylorhiza maculata with large inflorescences did not have better pollination success. The production of more flowers than the plant is able to fully support may have evolved as an ovary reserve in case of flower herbivory, or as a 'bet-hedging' strategy through which the plant can increase seed production in years with good pollinator availability.

Invasive plant species threaten native species and habitats causing ecologic, economic and social burden. When creating climate friendly solutions by utilizing plant biomasses in biogas and fertilizer production, safety should be ensured concerning the use of residues. This study concentrates on the treatment of biomasses containing invasive plant material by tunnel and windrow composting, and by farm-scale and laboratory-scale anaerobic digestion (AD) in mesophilic conditions. Germination of the nationally settled and harmful invasive species Lupinus polyphyllus Lindl. was investigated after these processes. In addition, the role of the conditions found in the processes that destroyed seeds were studied, such as the time of exposure, temperature and static pressure. Dormant seeds are well protected against harsh conditions and can survive through various stress factors, but also become vulnerable as more factors are combined and time of exposure is extended. Our results suggest that the risks involved for the utilization of harmful invasive species increase with mesophilic temperatures and single treatments if the processing conditions are not stabile. One-month treatment with windrow composting showed a high risk for dormant seeds of L. polyphyllus seeds to survive, whereby extending the processing time reduced it substantially. Hard coated seeds can thus be broken with a combination of thermophilic temperatures, moisture and static pressure.

Abstract. Due to often large variation in traits within and between populations, taxonomy of orchid species is problematic. In this study, we aim to assess the probability of sympatric speciation in mixed populations of nectarless Dactylorhiza incarnata varieties (incarnata, ochroleuca and cruenta). We conducted morphological, phenological and ecological measurements in five populations in Hiiumaa, western Estonia. In most populations, we did not find any differences to reveal genetic divergence between the varieties. In one population, however, differences in shoot and flower traits were found. This population also differed at the community level from the other four study populations. Composition of pollinator fauna on one hand, and the presence of rewarding companion species on the other, may cause selection to act towards different directions in different populations of nectarless species. In contrast to earlier studies with another nectarless orchid species, we found pollination success to be positively frequency-dependent, which may be caused by a stable pollinator preference for one of the varieties.

Polymorphism in petal colour is common in deceptively pollinated plant species. Most of the deceptively pollinated orchids are food frauds, and in most of them, the deception is not mimetic. These plants have conspicuously coloured flowers which they use as the main attractant of naive pollinators. In a field experiment, we studied the response of bumblebees and other types of flower visitors to colour differences between experimentally paired plants of Dactylorhiza maculata, a nectarless food‐deceptive species. In addition, pollen removal, an estimate of male fitness, and fruit production, an estimate of female fitness, were measured in the two colour variants. We found a trend of bumblebee preference for the dark‐coloured flowers, but other flower visitors (as a group) showed no preference for any colour variant. No difference was found in the reproductive success between the two colour variants of D. maculata. The lack of a difference in reproductive success between plants with pale and dark inflorescences, despite the observed trend of bumblebee preference for dark inflorescences, suggests that there is some balancing factor in the pollination of the pale inflorescences. An excess of visits by some nocturnal species (or a group of species) which favours the pale colour of D. maculata inflorescences or an excess of visits during day time by some flower visitors other than bumblebees preferring the pale inflorescences over dark ones may form such a balancing factor.

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