The Trap Architecture of Utricularia multifida and Utricularia westonii (subg. Polypompholyx)

Abstract

Utricularia are carnivorous plants which have small hollow vesicles as suction traps that work underwater by means of negative pressure and watertightness of the entrance for capturing small animal prey. Utricularia multifida and U. westonii have specific thick-walled traps, which are triangular in a transverse section but their functioning is unclear. Some authors suggest that the trap door in U. multifida acts as a simple valve without a suction trapping mechanism. Our main aim was to check the anatomical trap characters that are responsible for possible water outflow and maintaining negative pressure as main functional parts of the active trap suction mechanism in both species. Using different microscopic techniques, we investigated the ultrastructure of external trap glands, quadrifids, glands near the entrance (bifids, monofids), and also pavement epithelium. Quadrifids of both species have a similar structure to those known in other species from the genus, which possess the suction trap mechanism. Glands near the entrance in U. multifida and U. westonii , which are responsible for water pumping in other species, are typically developed as in other species in the genus and have pedestal cells which are transfer cells. The transfer cells also occur in glands of the pavement epithelium, which is again typically developed as in other species in the genus. Simple biophysical tests did not confirm reliably neither the negative underpressure formation in the traps nor the watertightness of the entrance in both species. Our anatomical results indirectly support the hypothesis that both species have suction traps like all other Utricularia species, but the biophysical data rather suggest a passive valve mechanism.

Snapshot prey spectrum analysis of the phylogenetically early-diverging carnivorous Utricularia multifida from U. section Polypompholyx (Lentibulariaceae)

“…With an average trap length of 2.3 mm (min: 1.8 mm; max: 2.7 mm) and width of 1.9 mm (min: 1.5 mm; max: 2.3 mm) ( S1 Table ), we observed a similar overall size as reported in previous literature [ 27 – 32 ].…”

“…multifida (and two close allies) has thick-walled traps, which are triangular in a transverse section, and an entrance region which can only be accessed from lateral sides [ 27 – 29 ]. This species has drawn some interest recently due to the fact that suction could not be observed in traps during laboratory experiments [ 30 – 32 ], although earlier investigations by Lloyd [ 28 ] state that its traps are indeed capable of suction. It was consequently theorized that U .…”

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

“…Lloyd 1942;Płachno et al 2014;Płachno et al 2017) and the functional ultrastructure of digestive glands (e.g. Płachno and Jankun 2004;Płachno et al 2019a). Most recently, Płachno et al (2020b) described structures of tubers in one Genlisea and two Utricularia species showing adaptation to abiotic stress (e.g.…”

Complexity and diversity of motion amplification and control strategies in motile carnivorous plant traps

“…Equally, comparing resettable versus ‘single use’ snap tentacles may elucidate trade-offs between movement speed and durability of trapping structures. Within the bladderworts, Utricularia multifida might be such an insight-providing outlier, because its traps did not show any firing events, or any water pumping activity in laboratory studies [ 86 , 93 ]. Hence, it is speculated that this species possesses non-motile eel traps similar to closely related corkscrew plants ( Genlisea ) [ 94 ].…”