In: Phyton, 51 Fasc. 1 (2011), S. 133-148, with 4 tables

Key words: Aquatic carnivorous plant, Lentibulariaceae, Utricularia, branching characteristics, plant biomass, investment in carnivory, growth rate, mathematical model.

Summary

Adamec L. 2011. Shoot branching of the aquatic carnivorous plant Utricularia australis as the key process of plant growth. – Phyton (Horn, Austria) 51 (1): 133–148.

Utricularia australis is a submerged rootless aquatic carnivorous plant with homogeneous shoots, exhibiting a great morphological and ecological plasticity and propagating only vegetatively by shoot branching. Detailed branching and morphometric characteristics of two U. australis populations were compared at two sites in the Trebon basin, Czech Republic. The sites, mesotrophic fishpond Ruda and oligotrophic sand-pit Cep, differed greatly in their trophic status and prey availability, and thus in plant size, fitness, and flowering. Flowering plants at Ruda were robust, highly branched, and produced on average totally 52 branches of various orders forming about 52.9 % dry weight of the total vegetative plant dry weight. All plants collected were on average relatively short, 12.5 % flowered, and 90 % contained a branch > 3 cm long with functional traps. In comparison, plants at Cep were much shorter, their internodes were strongly shortened, only 5 % of plants flowered, and only 60 % of plants bore distinguishable branches (on average only 1.1 branches a plant and 1.4 % of total plant dry weight). Shoot branching was recognized as one of the most important reasons for high plasticity of U. australis and for attaining high relative growth rate. Branching intensity of main shoots in U. australis might reflect discrete ecological conditions of each micropopulation. To understand the dynamic growth traits of aquatic carnivorous plants, a combination of branching characteristics and mathematical modelling is essential.