Clonality of an annual plant in a temporary environment: The case of whorled waterwort

• Clonality in plants with short life cycles.
• Depth is a key factor in the patterns of growth and sexual reproduction.
• Habitat recolonization is possible due to high seed production.

We tested whether an annual plant growing in unpredictable, temporary environments can simultaneously allocate its resources into vegetative growth and seed production. Sixty plants of Elatine alsinastrum were analysed for 24 traits associated with growth and sexual reproduction. The specimens originated from three depth fractions of temporary mid-field pools situated in western Poland. We found different patterns of plant growth and matching rates of sexual reproduction that corresponded to different water depths, i.e., shallow, intermediate, and deep. All the plants produced ramets and seeds, but the plants from the intermediate level had the highest number of both daughter ramets and seeds of the highest mass compared to the plants from the shallow- and deep-water conditions. Our results show that in E. alsinastrum both clonal vegetative growth and a high seed production occur. Such behaviour of plants in highly disturbed habitats diverges from the annual and clonal plant life strategies described thus far. The case of E. alsinastrum challenges a general ecological concept assuming that clonality involves only perennial plants.