THE MORPHOLOGICAL CORRELATES OF PREY CAPTURE AND RESOURCE PARASITISM IN PITCHERS OF THE CARNIVOROUS PLANT SARRACENIA-PURPUREA

To infer the functional significance of morphological variation among pitchers of the carnivorous plant Sarracenia purpurea, I measured 8 traits on 87 pitchers and recorded prey captures and frequency of occlusion by spider webs for 47 days. A principal component analysis summarized 78% of the variance in the morphological traits on three component axes, which expressed variation in pitcher size, in pigmentation and available nectar and in pitcher height, respectively. Regression analysis found that the biomass of prey captured was significantly dependent only on the component of variation in pitcher size. However, the number of prey caught was significantly dependent on the component of variation in pitcher size and the component of variation in pigmentation and available nectar. The frequency of inhabitation by spiders was significantly dependent on the components of pitcher size and height. Thus, a relationship was demonstrated between pitcher morphology, prey capture and frequency of resource parasitism.