标题：Difference in Floral Traits, Pollination, and Reproductive Success between White and Blue Flowers of Gentiana leucomelaena (Gentianaceae) in an Alpine Meadow
摘要：The blue-white gentian, Gentiana leucomelaena (Gentianaceae), bears two colors of flowers (blue and white) within populations and on individual plants. We tested the hypothesis that these flower morphs have different mating systems associated with differences in pollinator species and visitation rates. This hypothesis was driven by the fact that colorful flowers are often more likely to be pollinated by diverse animal pollinators, and by the observation that white G. leucomelaena flowers always blossom earlier than blue ones in early spring, when few pollinators are available. This hypothesis was investigated by determining the pollination success, daily duration of flower opening, flower life span, the number of pollen grains and ovules per flower, pollinator visitation rates, and seed output for both color morphs during the flowering season of 2009. Hand-pollination and pollinator-exclusion experiments were also conducted to determine whether the two color morphs differed in their ability to self-pollinate. In general, blue flowers were found to have a trait combination that favors a significantly higher degree of pollinator specificity and cross fertilization, whereas white flowers were characterized as pollinator generalists and self-fertilizing. We speculate that the difference in the floral structure and function between blue and white flowers and their coexistence are likely adaptive in unpredictable and often pollinator-limited environments such as those found in the alpine meadows of the Qinghai-Tibet Plateau.
