Presence of fruits decreases probability of retaining flowers in a sequentially flowering plant

Both intrinsic and extrinsic plant processes affect the fate of flowers along an inflorescence in sequentially flowering plants. In a study recently published in AoB PLANTS, Jadeja & Tenhumberg investigated mechanisms underlying variation in fruiting patterns of sequentially flowering plants using the wild flower Yucca glauca (Family: Agavaceae). These plants start opening flowers on the bottom of an inflorescence and then gradually open new flowers all the way along the raceme.

Receptive distal Yucca flowers
Receptive distal Yucca flowers. Three flowers are protected against herbivory and natural pollination. Image credit: Jadeja & Tenhumberg.

The authors considered whether the intrinsic processes of resource competition between fruits and flowers, or plant architecture (flowering and fruiting position) explain the low probability of retaining distal flowers in Y. glauca. They also investigate how extrinsic seed herbivory may affect the intrinsic processes of flower retention. Through a field experiment comparing flower retention across various inflorescence treatments, the study showed that plants are more likely to abort distal flowers when growing basal fruits are present. This is likely because limited fruiting resources are disproportionately accumulated by basal fruits that are stronger resource sinks than flowers. Previous studies have tested this mechanism in cultivated plants however this study shows some of the first clear evidence for this mechanism in a wild flower population.