Ecology and vegetative morphology of the carnivorous plant Utricularia dichotorna (Lentibulariaceae) in New Zealand

Abstract

The occurrence of the carnivorous plant Utricularia dichotoma (including U. monanthos and U. novae‐zelandiae) within different habitats throughout New Zealand was studied. Qualitative investigations on its ecology focused on plant sociological criteria and soil characters, including the qualitative amount of water and soil chemistry. A list of associated plant species is also provided. Results indicate that U. dichotoma prefers open wet habitats. Once established, however, it may grow in fertile and permanently submerged sites. The vegetative morphology of the species from different populations was also examined and correlated with ecological factors. Utricularia dichotoma basically consists of runner stolons, from each node of which arise various combinations of leaves, bladders (traps), and anchor and runner stolons. Plants of some populations also show simply branched, bladder‐bearing intermediate types of anchor and runner stolons (designated “simple stolons"). Some nodes of runner stolons support the development of a peduncle. In the populations studied, the onset of a dry sunny period was typically followed by flowering. Plants from Kopouatai Peat Dome exhibited certain distinctive morphological features not found in other populations, including more bladders per plant. Among the populations studied, the corolla, peduncle, foliage leaf, and bladders occasionally exhibited a reddish or purple pigmentation, apparently developed in a response to different environmental factors.

Keywords:

• Utricularia dichotoma
• Lentibulariaceae
• carnivorous plant
• vegetative morphology
• anthocyanins
• stolon
• traps
• vegetation ecology
• wetlands