Floral Biology and Breeding System ofAngadenia berteroi(Apocynaceae): Why Do Flowers of the Pineland Golden Trumpet Produce Few Fruits?

Angadenia berteroi is a tropical perennial subshrub with large yellow flowers that sets very few fruits in its native pine rockland habitat. To learn more about the breeding system of this rare species, we collected seeds from two populations and grew plants for greenhouse study. The flowers open before sunrise. They have a complex floral arrangement (the anthers form a conical structure surrounding the stigma, which has a secondary pollen presentation) that promotes outcrossing from visits by long-tongued pollinators. Hand-pollinations show that A. berteroi is mostly self-incompatible, with greatest fruit set, fruit length, and seedling emergence resulting from crosses between unrelated individuals. The low fruit set observed in natural populations may be due to low visitation by pollinators, matings between closely related individuals, or both.