Abstract:To explore the distribution characteristics and evolutionary driving mechanisms of flower colors of woody angiosperms in Gansu Province, this study identified 1 273 species of woody angiosperms based on literature data, and collected their information on flower colors and altitudinal distribution. Chi-square test and variance analysis were adopted to analyze flower color composition and its differentiation across different life forms. A total of 1 273 flower color records were obtained and classified into six categories. The yellow flower group accounted for the largest proportion (35.19%), while the blue flower group had the lowest proportion (1.41%). Flower color composition differed significantly among life forms. Yellow flowers were dominant in arbors, shrubs and woody vines, with the highest proportion found in woody vines. These plants were distributed at altitudes from 550 m to 4750 m, and yellow flowers prevailed across all altitudinal zones. Geographical environmental factors regulated flower color distribution along the altitudinal gradient. Phylogenetic analysis revealed that dominant flower colors including white, red and yellow, presented strong phylogenetic conservatism and were mainly constrained by genetic background. By contrast, special flower colors such as green, purple and blue showed no obvious phylogenetic signals, and their evolution was primarily driven by local environmental selection.
