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Our aim was to investigate the influence of weather conditions and prey on the leaf-trapping behaviour of insectivorous plant Drosera rotundifolia (Droseraceae) in the natural habitat.
Continuous, non-manipulative observations on two sundew plants in Northern Russia and two plants in Middle Russia lasted 72 hours each. We estimated the shape of the leaf blade, the degree of slime secretion, percentage of curved margin tentacles and the number of captured prey for each of sixteen leaves chosen for the study.
Our observations show that different characteristics of leaf blade changed independently both on each other and on the presence of prey. The correlated behaviour of leaf blades from different plants also indirectly shows the absence of dependence between trapping leaves behaviour and prey. However, our experiments with artificial feeding in natural conditions show clear leaf reaction to the prey.
We propose that in natural undisturbed conditions changes of the leaf blade characteristics are casual and are augmented by the external factors such as relative air humidity, atmosphere pressure and presence of the prey on the leaf blade.