Nectar: its production and functions in trumpet creeper

Science. 1975 Jul 25;189(4199):289-91. doi: 10.1126/science.189.4199.289.

Abstract

Studies of the trumpet creeper, Campsis radicans (L.) Seem. (Bignoniaceae), reveal five distinct nectary systems, a phenomenon never before reported among temperate zone plants. Ant activity, centered around the four extrafloral systems, clearly demonstrates the ant-guard symbiosis usually associated only with tropical or subtropical species. Floral nectar, an attractant for hummingbird and bumblebee pollinators, differs chemically from the ant-attracting nectar produced extraflorally.