Effects of Aquatic Conditions on Trap Structure in the Submerged Form of Drosera intermedia Hayne

Carnivorous plants possess highly specialized trap structures that enable the acquisition of nutrients from captured animals. This study investigated whether the aquatic environment influences the architecture of glandular emergences (tentacles) in the submerged form of Drosera intermedia. Morphometric analyses were performed on tentacles from plants growing in sandy terrestrial habitats, emergent wetland habitats, and submerged aquatic habitats. Significant differences in tentacle morphology were detected among habitat types. Emergent plants generally developed the largest tentacles and tentacle heads, whereas submerged plants exhibited shorter marginal tentacles and smaller glandular heads. In contrast, the shape of both marginal and central tentacle heads remained relatively stable across habitats, indicating stronger developmental conservation of this trait. Nevertheless, the submerged form differed significantly in the morphology of central tentacle heads. These results demonstrate that aquatic conditions substantially modify the structure of carnivorous emergences, revealing pronounced phenotypic plasticity in the carnivorous syndrome of D. intermedia. The reduction in tentacle size under submerged conditions may reflect altered functional demands associated with prey capture, changes in mucilage effectiveness, and the mechanical constraints imposed by the aquatic environment. However, differences in light availability, nutrient status, and other habitat characteristics may also contribute to the observed patterns. At the same time, the persistence of glandular structures indicates the retention of the carnivorous apparatus despite prolonged submergence. This study highlights the remarkable developmental flexibility of D. intermedia and provides new evidence that trap morphology in carnivorous plants may be highly responsive to environmental conditions.