Ambophily and evidence of hydrophily as a new pollination strategy in Eleocharis (l.) Roem. & Schult (Cyperaceae)

Aquatic plants can reproduce through abiotic or biotic pollination. In Cyperaceae anemophily is plesiomorphic, but studies have registered floral visitors in some genera, including Eleocharis. Wind and insects, therefore, can act together in the pollination, characterising ambophily. However, so far there has been no evidence that water could also be a pollen vector in this family.

Expand understanding of the pollination mechanisms in Cyperaceae.

We analysed the floral biology, pollen to ovule ratio, floral visitors, performed pollen vector exclusion experiments, characterised the floral colour in the models of insect vision and analysed the chemical composition of floral scent of Eleocharis geniculata and E. mutata.

Both species have anemophilous attributes. In Eleocharis mutata, wind was an effective pollen vector, increasing the fruit set. Individuals of E. geniculata exposed to water were more likely to produce fruits (p < 0.01). Eight species of insects were recorded as floral visitors of E. mutata, among which an Ephydroidea fly acting as the main pollinator. Flowers of both species had the same scent as the vegetative parts, and were shown to be visible and distinguishable from the background in both Hymenoptera and Diptera vision models.

Our results suggest a new pollination strategy (hydrophily in E. geniculata), and another case of ambophily in Cyperaceae.