Evolutionary history and climate conditions constrain the flower colours of woody plants in China

Abstract In this study, we investigated (i) the differences in flower colour composition among growth forms of woody plants in China and (ii) the influences of biogeographic regions, evolutionary age and climatic conditions on geographic variation in the proportions of different flower colours. Using distribution maps and flower colour information (white, red, yellow, yellow-green, green and blue-purple) of 7673 Chinese woody plant species and a dated genus-level phylogenetic tree, we compared flower colour composition among different growth forms (shrubs, trees and lianas). We further estimated the relationships of geographical patterns in the proportions of different flower colours with seven different biogeographic regions, evolutionary age and different contemporary climatic variables. Compared with trees or lianas, shrubs showed a higher proportion of species with anthocyanin-based red and blue-purple flowers. The geographic patterns of flower colour composition of woody plants in China were strongly influenced by regional effects and contemporary climate, especially precipitation and ultraviolet B irradiance. The proportion of species with presumably bee-pollinated yellow and blue-purple flowers and stress tolerant anthocyanin-based red and blue-purple flower colours tended to be high in the northwestern part of China. Green flowers tended to evolve earlier than others, but evolutionary age had quite weak influences on the geographic pattern of flower colours. Our results reflect both evolutionary and environmental constraints on the distribution of flower colours of woody plants in China.