Bladder control in Utricularia macrorhiza: lake-specific variation in plant investment in carnivory

• Published in: Ecology (Durham) Vol. 72; no. 2; pp. 728 - 734
• Main Authors: Knight, Susan E., Frost, Thomas M.
• Format: Journal Article
• Language: English
• Published: Washington, DC The Ecological Society of America 01-04-1991; Ecological Society of America; Brooklyn Botanic Garden, etc
• Subjects: ANATOMIA DE LA PLANTA; ANATOMIE VEGETALE; Animal, plant and microbial ecology; Animals; AQUATIC PLANTS; Biological and medical sciences; Botany; Carnivores; CARNIVOROUS PLANTS; ECOLOGIA VEGETAL; Ecology; FEUILLE; Flowers & plants; Fundamental and applied biological sciences. Psychology; HABITAT; HABITATS; HOJAS; Insectivorous plants; Investment plans; LAC; LAGOS; LAKES; LEAVES; LENTIBULARIACEAE; Limnology; MINERALES; MINERALS; MINERAUX; Nutrient solutions; PHYTOECOLOGIE; Planned investments; PLANT ANATOMY; PLANT ECOLOGY; Plant nutrition; PLANTAS ACUATICAS; PLANTAS CARNIVORAS; PLANTE AQUATIQUE; PLANTE CARNIVORE; Plants; WISCONSIN; Lakes; Nutrient; Plant leaf; Carnivorous plant; Capture
• ISSN: 0012-9658; 1939-9170
• DOI: 10.2307/2937212

Differences among habitats in the relative availability of prey and inorganic nutrients suggest that carnivorous plants should vary their investment in prey capture. We tested this hypothesis using the carnivorous plant Utricularia macrorhiza, which is common in lakes exhibiting a broad range of nutrient conditions. We assessed U. macrorhiza investment in carnivory as the density of prey-capture bladders per leaf. Field surveys revealed that the number of prey-capture bladders per leaf varied significantly among lakes but was highly consistent within a habitat. Differences in the number of bladders reflects an increasing proportion of plant biomass in bladders. Contrary to our initial hypothesis, the number of bladders was positively, not negatively, correlated with the specific conductance of a plant's habitat water. Reciprocal transplant experiments of plants from lakes with many or few bladders per leaf revealed that the number of bladders per leaf is plastic, capable of changing on new leaves over a period of a few weeks. Experimental manipulations of animal prey indicated that a plant's bladder number per leaf is a direct response to water chemistry rather than to prey availability.