Mayapple (Podophyllum peltatum) is a self-incompatible woodland herb that exhibits clonal growth and does not produce nectar. It often exhibits low fruit set and is reputed to rely on other nectar-producing plants to attract insect pollinators. We attempted to assess the relative importance of mayapple patch size and the abundance of other flowering plants on mayapple’s pollination and fruit production in the Cleveland, Ohio Metroparks. One hundred and twenty patches with at least five flowering stems were located along transects in four forested areas of the Metroparks. Eighteen patches were hand-pollinated; the rest were allowed to be naturally pollinated. Pistils were collected from half the naturally pollinated flowers and analyzed for the presence of pollen tubes using fluorescence microscopy. Fruit development was monitored every 10 days through the end of July 2008 when fruits were collected and examined for seed production. Results/Conclusions
Hand-pollinated flowers produced fruits at a higher rate (63%, n=90) than did naturally pollinated flowers (22%, n=102), and natural fruit set varied significantly across forested areas (3 to 31%). Regressions of fruit number per patch vs. patch size (number of flowering stems per patch) revealed no significant relationships. A significant correlation between the abundance of flowering plants in the vicinity of mayapple and the number of pollen tubes per stigma (r = .467, 0.02 < p < 0.05, n = 24) was found in one area, but regressions of fruits per patch vs. flowering plant abundance were not significant. Although our data indicate that mayapple fruit production is strongly limited by pollination, they also suggest that neither patch size nor flowering plant abundance has a major influence on the rate at which mayapple flowers produce fruits.
