Wecomparedthe rate of pollen tube growth following self-and cross-pollinations both among and within flowers of two clonesof Dianthus chinensis L. For among-flower comparisons, both styles of a flower were pollinated with either self-or cross-pollen. Within-flower comparisons weremade between the two stylesof the same flower, one of which was self-pollinated and the other cross-pollinated. Comparisons between flowers indicatedthat self-pollen grewslowerthan cross-pollen in both clones. However, differences in the growth rate of pollen tubes from selfand cross-pollinations weregreaterwhencomparisonsweremade between the two stylesof the same flower than when pollinations were made in different flowers. These results suggest the existence of interstyle interactions in pollen tube growth.

Selection can occur in the pistil, during a series of stages that include both pre-zygotic (pollen germination, pollen tube growth, and fertilization) and post-zygotic events. This study explores the extent to which selection, at this level, could be due to the environmental conditions under which the maternal parent is growing. Five plants of Mimulus guuatus, tolerant to copper, were vegetatively cloned and each clone was grown in control and in solutions to which copper was added. The maternal plants received pollen from plants either tolerant or sensitive to copper. Seeds and ovules were counted to estimate the number of seeds/capsule, the seed/ovule ratio, the percent fertilization, and the proportion of zygotes aborting for each clone, treatment and pollen source combination.There were large differences among the pollen recipients for each ofthe measurements. However, there was a consistent pattern to seed production depending on the pollen source and copper treatment. The seed/ovule ratio was unaffected ifpollen came from tolerant sources but was reduced by an average of24% for both copper supplemented treatments ifpollen came from copper sensitive sources. Thus, the data indicated that selection due to environmental factors could occur within the pistil. Differences in percent fertilization were not statistically significant, but the seed/zygote ratio showed a pattern that was similar to seed production suggesting that abortion of immature seeds was responsible for most of the difference in seed production.

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Selection can occur in the pistil, during a series of stages that include both pre-zygotic (pollen germination, pollen tube growth, and fertilization) and post-zygotic events. This study explores the extent to which selection, at this level, could be due to the environmental conditions under which the maternal parent is growing. Five plants of Mimulus guttatus, tolerant to copper, were vegetatively cloned and each clone was grown in control and in solutions to which copper was added. The maternal plants received pollen from plants either tolerant or sensitive to copper. Seeds and ovules were counted to estimate the number of seeds/capsule, the seed/ovule ratio, the percent fertilization, and the proportion of zygotes aborting for each clone, treatment and pollen source combination. There were large differences among the pollen recipients for each of the measurements. However, there was a consistent pattern to seed production depending on the pollen source and copper treatment. The seed/ovule ratio was unaffected if pollen came from tolerant sources but was reduced by an average of 24% for both copper supplemented treatments if pollen came from copper sensitive sources. Thus, the data indicated that selection due to environmental factors could occur within the pistil. Differences in percent fertilization were not statistically significant, but the seed/zygote ratio showed a pattern that was similar to seed production suggesting that abortion of immature seeds was responsible for most of the difference in seed production.

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