Living between land and water – structural and functional adaptations in vegetative organs of bladderworts

Abstract

Aims The carnivorous Utricularia (Lentibulariaceae) has an anatomically simple and seemingly rootless vegetative body. It occupies a variety of wetlands and inland waters and shows a broad range of life forms. Here, we aimed to elucidate structural and functional traits in various hydric conditions. Furthermore, we intended to evaluate morpho-anatomical adaptations in correlation with life forms. Methods Morpho-anatomical characteristics typical for hydrophytes of all life forms were investigated by light microscopy on 13 Utricularia taxa, compared to one Pinguicula and two Genlisea taxa, and assessed by multivariate analyses. Results Vegetative structures of Utricularia and Genlisea showed reduced cortical, supporting, and vascular tissues. With increasing water table, leaves were thinner, and narrower or dissected, and submerged organs tended to contain chloroplasts in parenchymatic and epidermal cells. In some main stolons, an endodermis with Casparian strips was visible. Large gas chambers, including a novel ‘crescent’ and a special ‘hollow’ aerenchyma pattern, were found in amphibious to free-floating taxa. Conclusions The evolutionary transfer of carnivory from aerial to subterranean organs in Genlisea, and even more in Utricularia, coincides with a highly simplified anatomy, which is adapted to a broad variety of hydric conditions and compensates for structural innovations in the uptake of nutrients.

Development, Diversity and Dynamics of Plant Architecture in Utricularia subgenus Polypompholyx – Towards Understanding Evolutionary Processes in the Lentibulariaceae

“…Thus, together with their taxonomic relevance, forms of leaves and leaf apices are strongly correlated to the habit and in turn to the habitat and water levels. This corroborates the findings of Reut et al (2021),…”

“…(Taylor, 1989;Jobson et al, 2017Jobson et al, , 2018bReut et al, 2021). Reut et al (2021) investigated morpho-anatomical adaptations of Utricularia (including 7 taxa of subgenus Polypompholyx) to submergence and a life in the water column and found that leaves tend to be narrower in submerged hydrophytes and dissected in free-floating hydrophytes, confirming similar observations on heterophyllous amphibious plants (e.g. Nakayama et al, 2017) and obligate hydrophytes (e.g.…”

“…The material of Pinguicula and Utricularia was carefully rinsed, cleaned from debris, fixed as in Reut et al (2021), and pre-examined under a stereo microscope. A part of the material was selected for further examination, dehydrated, and critically-point dried using liquid CO 2 .…”

“…of the root) that were of less importance or were replaced by the trap function (e.g. uptake of nutrients) for a successful propagation (Rutishauser, 2016(Rutishauser, , 2020Reut & Płachno, 2020;Reut et al, 2021). The traps of Genlisea and Utricularia deploy the functionality in moist to submerged habitats, with Utricularia being physiologically the most dependent on free water (e.g.…”

“…runner stolons, water shoots, air shoots, and floaters), the more it adapted to submergence and to a life in the water column (cf. Taylor, 1989;Jobson et al, 2018b;Reut et al, 2021).…”