The non-indigenous invasive, Lonicera japonica, is a woody vine with a well-documented capacity for vegetative spread. Few data exist on its potential for establishment by seed, but anecdotal reports span the range from abundant seed reproduction to little seed reproduction. Atypical for an invasive alien, L. japonica is biotically-pollinated and xenogamous, requiring pollen from a genetically distinct individual for fruit set. I addressed the question of whether the services provided by the locally-available pollinator community were adequate for fruit set of L. japonica within its naturalized range. Hand-pollinations indicated that fruit set of L. japonica in Arkansas was pollinator limited. Naturally-pollinated control shoots produced fruit from 17.4% of their flowers, but the hand-pollinated flowers had a fruit set of 78.7%, an increase of over 4.5 times. As expected for a plant reported to be biotically pollinated and xenogamous, the shoots with pollinators excluded set fruit on only 2.1% of the flowers. In a survey of seven different sites along the western edge of the naturalized range of L. japonica, we found an average fruit set on primary shoots of 11.5+1.4% (mean+SE), while the secondary shoots averaged 20.1+2.8%. These results indicate that sexual reproduction by L. japonica is limited along the western edge of its naturalized range, and that the invasive character of L. japonica in this area is largely due to its prolific vegetative spread. Because this is one of the few empirical data sets on sexual reproduction by this important plant within its naturalized range, we do not extend our conclusions to other areas of the US, but instead emphasize the importance of documenting geographic differences in the reproductive potential of L. japonica.

Key words: fruit set, invasive plant, Lonicera japonica, pollination