Nonrandom Fruit Production in Campsis radicans: Between-Year Consistency and Effects of Prior Pollination

The tendency in Campsis radicans for fruits to be produced from certain crosses was consistent between years. This increases the likelihood that observed patterns are genetically based. Early in a season, plants were more selective about which donor they accepted pollen from, as measured by the parentage of mature fruits. Field experiments indicated that this increase in selectivity was related not to date, but to the number of prior pollinations and developing fruits in an inflorescence, and therefore presumably to the availability of resources. These differences in fruiting indicate a non-male component to selectivity (since pollen source was controlled). That the acceptability of pollen from particular donors depends on the resource status of the inflorescence means that the distinction between pollen limitation and resource limitation of fruit production is not a sharp one. A model is proposed to account for patterns of fruit production with respect to paternity in Campsis radicans.