Factors affecting prey-derived nitrogen in flowers of the purple pitcher plant, Sarracenia purpurea

Abstract

The Purple Pitcher Plant, Sarracenia purpurea, is a carnivorous plant that lives in low-nitrogen environments such as bogs. This study looked at 50 pitcher plants in Mud Lake Bog, Michigan and used stable nitrogen isotope ratios and environmental and morphological factors to determine levels of prey-derived nitrogen in pitcher plant flowers and the factors that correlated with these nitrogen levels. It was hypothesized that flowering structures would be more reliant on insect-derived nitrogen than the pitchers themselves, and so expected to see an increase in prey-derived nitrogen in flowers. Significantly higher levels of insect-derived nitrogen were found in flowering structures compared to pitchers, with a mean in flowers of 73% prey-derived nitrogen. Pitcher size, color, soil temperature, surrounding biomass, number of flowers, and captured insect biomass all correlated with variation in prey-derived nitrogen values in the flowers. It was concluded that flowering structures preferentially received prey-derived nitrogen over pitchers, and that several environmental and morphological factors combine to affect the percentage of insect-derived nitrogen being used to produce these flowers.