The free-floating aquatic plant Utricularia australis has typically subsurface shoots and subaerial showy in- florescences. To find it growing with large populations among benthic Chara stands at 4–6 m depth in two Central Italian lakes, is a phenomenon that was never previously reported. Production of showy chasmogamous flowers at this depth makes such finding yet increasingly intriguing. Here we make quantitative-qualitative comparisons of morphological characters among subaerial and underwater flowers taken from diverse sites in Central Italy. Environmental data were used to delineate differences between superficial and underwater habitats where flowering U. australis populations were found, and to help explain these extraordinary findings. Although similar, the subaerial and underwater flowers did show some differences, the most important being the length of the floral scape. Underwater scapes were around three times longer than those emerged. This might be a typical phototropic-response or a failed attempt to get flowers above water surface for allowing entomophilous polli- nation, or a redundant morpho-physiological trait as a result of a recent ecological move. Underwater flowers were generally smaller, but they did have longer styles, nectar signalling was less obvious, thinner petals, mucous-coated pollen (subaerial pollen is dry and grainy). Both types of flower were sterile, producing abortive fruits. Possibility of underwater ecological conditions causing stress-induced flowering is also proposed. A lack of water movement is an important ecological requirement for U. australis growth and could explain why large populations have been found in deep water far from its typical habitat.

Unusual underwater flowering of Utricularia australis populations: a botanical enigma? / Ceschin, S.; Pelella, E.; Azzella, M. M.; Bellini, A.; Ellwood, N. T. W.. - In: AQUATIC BOTANY. - ISSN 0304-3770. - (2022).

Unusual underwater flowering of Utricularia australis populations: a botanical enigma?

M. M. Azzella;
2022

Abstract

The free-floating aquatic plant Utricularia australis has typically subsurface shoots and subaerial showy in- florescences. To find it growing with large populations among benthic Chara stands at 4–6 m depth in two Central Italian lakes, is a phenomenon that was never previously reported. Production of showy chasmogamous flowers at this depth makes such finding yet increasingly intriguing. Here we make quantitative-qualitative comparisons of morphological characters among subaerial and underwater flowers taken from diverse sites in Central Italy. Environmental data were used to delineate differences between superficial and underwater habitats where flowering U. australis populations were found, and to help explain these extraordinary findings. Although similar, the subaerial and underwater flowers did show some differences, the most important being the length of the floral scape. Underwater scapes were around three times longer than those emerged. This might be a typical phototropic-response or a failed attempt to get flowers above water surface for allowing entomophilous polli- nation, or a redundant morpho-physiological trait as a result of a recent ecological move. Underwater flowers were generally smaller, but they did have longer styles, nectar signalling was less obvious, thinner petals, mucous-coated pollen (subaerial pollen is dry and grainy). Both types of flower were sterile, producing abortive fruits. Possibility of underwater ecological conditions causing stress-induced flowering is also proposed. A lack of water movement is an important ecological requirement for U. australis growth and could explain why large populations have been found in deep water far from its typical habitat.
2022
bladderwort; aquatic plant; underwater flowering; stress induced flowering; chasmogamous flower; lake environment
01 Pubblicazione su rivista::01a Articolo in rivista
Unusual underwater flowering of Utricularia australis populations: a botanical enigma? / Ceschin, S.; Pelella, E.; Azzella, M. M.; Bellini, A.; Ellwood, N. T. W.. - In: AQUATIC BOTANY. - ISSN 0304-3770. - (2022).
File allegati a questo prodotto
File Dimensione Formato  
Ceschin_Unusual underwater_2022.pdf

solo gestori archivio

Tipologia: Versione editoriale (versione pubblicata con il layout dell'editore)
Licenza: Tutti i diritti riservati (All rights reserved)
Dimensione 4.24 MB
Formato Adobe PDF
4.24 MB Adobe PDF   Contatta l'autore

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1639999
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 2
  • ???jsp.display-item.citation.isi??? 2
social impact