Within the Asimina genus, one of the only temperate generas within the Annonaceae, seven of the eight species are endemic to the southeast and are primarily found in Florida. One such species is the netted pawpaw (Asimina reticulata), which is widespread throughout peninsular Florida and southern Georgia. Similar to Asimina obovata, its more rare congener, A. reticulata exhibits an increase in flowering post fire and has notoriously low fruit set. To gain insight into its distribution and reproductive success, we posed three main questions: [1] how does time-since-fire (TSF) and pollinator visitation influence the reproductive success of this species, [2] is it pollinator dependent, and [3] does outcrossing increase reproductive success? In 2016, we studied 157 plants in three flatwoods burn units (last burned in 2015, 2012, or 2001) and one grazed pasture at Archbold Biological Station in south-central FL.
Results/Conclusions
Plants in pasture and recently burned flatwoods exhibited greater flower, fruit, and seed output- suggesting that habitat openness may promote competitive release or increased pollinator visitation. Pollinator visitation was greatest on plants within the 1y TSF, and the hairy flower scarab was the most prevalent visitor across all sites. Autogamously-crossed flowers produced no fruit, confirming that seed production is pollinator dependent. While fruit retention [10.0%] and seed germination [27.8%] were low following geitonogamous-crossing, close and far outcrossing increased retention [30.8%, 39.6%] and germination success [41.6%, 46.4%]. This research suggests that A. reticulata reaches its maximum reproductive potential in open areas following outcrossing events, and that low fruit set may be due to a lack of an effective pollinator, resulting in inbreeding depression. Additionally, an investigation into raccoons as fruit consumers and potential seed dispersers suggests that seeds may benefit from gut scarification. Influenced by site factors, pollinators, and genetics, sexual reproduction in the netted pawpaw is likely to vary widely in both space and time.