nectar

To establish if foliar herbivory causes changes in floral rewards that could alter floral visitation, we selected another 30 pairs of plants (15 pin and 15 thrum) of P. angustifolia. On each pair, we selected branches with inflorescences at the bud stage to serve as locally-induced, systemically-induced, and control branches and applied grasshopper herbivory treatments as described above. After 3 days, grasshoppers and bags were removed. From a subset of the same inflorescences (5 pin and 6 thrum), we also collected nectar on one randomly chosen flower. Nectar volume was measured using 2µL microcapillary pipettes (Drummond Scientific Company, Broomall, PA). The sugar concentration was estimated using a handheld refractometer (Reichert Digital Brix/RI-Chek). Due to low nectar volumes, all samples were diluted in 0.1 mL distilled water prior to taking concentration measurements. The concentration of the floral nectar was then calculated as the measured solution concentration multiplied by the ratio of the final solution volume to the collected nectar volume. The first column shows the flower morph: pin (P) and thrum (T). The second column is the volume in microliters of nectar present in the flower. The third column is the concentration of the nectar in each flower. The fourth column is the treatment of each branch: C control, S systemic induction and L local induction. The fifth column is the block of each pair of plants.