Floral biology and breeding system in Erythrina flabelliformis, a hummingbird-pollinated shrub of the desert southwest

Background/Question/Methods

Erythrina flabelliformis reaches its northernmost distribution in the Sky Islands of southeastern Arizona. We examined the role of floral phenology, nectar production, and breeding system in reproductive success in a marginal population of Erythrina from the Chiricahua Mountains in SE Arizona, and compared these traits to individuals from central populations in the Sierra Madre Occidental Mountains, Sonora, Mexico. 

Results/Conclusions

Flowers last two days, and patterns of flowering and nectar production encourage between-plant movements, promoting outcrossing in the population. Fruit set is dramatically higher in  years of high hummingbird visitation. The timing of flowering, the nectar secretion curves and the estimates of nectar production per flower and per plant suggest that Erythrina may play an important in providing resources for local breeding populations of hummingbirds.