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Kosteletzkya virginica (Malvaceae) is an herbaceous species native to North America that was introduced into China in 1993. Flowers are viable for one day and contain five independent lobes with curving stigmas that are pollinated either by insects or by stylar movement. If pollinated, stigma lobes remain erect, but if pollination fails, stigmas curve towards the anther, eventually making contact and self-fertilizing. We measured 1) the effect of pollination on stigma lobe curvature, 2) the effect of self and outcrossed pollen on pollen tube growth, and 3) the fertility of flowers in which the number of pollinated stigmas varied. Results indicate that the most important signal to halt stigma curvature occurs when the pollen tube grows beyond the stigma lobe. This response was not influenced by the amount of pollen received. The stigma lobes (n=121) halted curvature after receiving from 1 to 162 pollen grains. Experimental pollination from one to four stigmas did not inhibit curvature of adjacent un-pollinated lobes. Under open-pollination conditions, the flowers with five stigmas produced significantly more seeds than flowers with one to four stigmas (U=61.00, W=881.00, P |
