Evolution of flower-leaf sequences in temperature forests
Scientific interest in flower-leaf sequences goes as far back as the late 1800’s. Several hypotheses have been put forth to explain the adaptive function of hysteranthy (flowering before leaves), but tests of these hypotheses are rare.
Through modeling the relationships between FLSs and functional traits associated with each hypothesis, we found that pollination syndrome, flowering time, water limitation and phylogeny all drive inter-specific variation in FLSs in some species.
Because of this concurrent support for multiple hypotheses should be starting point for the study of flower-leaf sequences.
Environmental drivers of sequence variation
It is well established that photoperiod and temperature are the primary environmental cues for both flower and leaf phenology. However, inter-annual variation in FLS patterns is high, suggesting that the cues are integrated differently among these phases.
We used growth chambers to manipulate climate conditions for dormant twig cuttings for a suite of temperate woody plants and found that leaf phenology was more responsive to changes in chilling than flower phenology.
Flower-leaf sequences in the genus Prunus
The genus Prunus displays significant variation in flower-leaf sequences patterns among species. Using herbarium species, we investigated the morphological and environmental factors that associate with the diversity of FLS patterns in this genus and found flowering-first is associated with aridity and smaller flower displays, suggesting this phenology syndrome may have evolved to increase drought tolerance and pollinator visibility