为了解白花野牡丹(Melastoma candidum f. albiflorum J. C. Ou)的开花进程、花部形态特征及访花昆虫的种类和访花行为,分别于2011 年和2012 年对栽培于深圳市中国科学院仙湖植物园的白花野牡丹花期进行观察和统计分析。结果表明:白花野牡丹的单花花期约12 h,7:00 雌蕊柱头从即将开放的花蕾中伸出、8:00 左右花朵半开放、8:30 左右花瓣完全展开、16:00 左右花瓣开始闭合、19:00 左右花瓣完全闭合,翌日花瓣不再开放并逐渐萎蔫,至第4 天花部完全脱落。白花野牡丹的花序为近头状的伞房花序,每个花序有3 ~8 朵花;雌蕊1 枚;雄蕊2 轮(5+5,6+6),内轮雄蕊较短、而外轮雄蕊较长;不分泌花蜜。白花野牡丹花期的访花昆虫有2 目5 科13 种,其中传粉昆虫有2 科6 种, 包括领木蜂(Xylocopa collaris Lepeletier)、东亚无垫蜂[Amegilla (Zonamegilla) parhypate Lieftinck]、蓝彩带蜂(Nomia chalybeata Smith)、彩带蜂(Nomia sp.)、中华蜜蜂(Apis cerana cerana Fabricius)和绿芦蜂(Pithitis smaragdula Smith)。这6 种传粉昆虫的访花行为、访花规律及传粉效率各异,其中,领木蜂、东亚无垫蜂、中华蜜蜂和绿芦蜂的日活动规律为单峰型,访花高峰期均在10:00 或11:00;而蓝彩带蜂和彩带蜂的日活动规律为双峰型,2 个访花高峰期分别在10:00 和15:00。花瓣开始松动时,小体型的中华蜜蜂和绿芦蜂开始传粉;随着花瓣继续开放,中等体型的蓝彩带蜂和彩带蜂成为主要传粉者;花瓣完全开放后,大体型的领木蜂和东亚无垫蜂成为主要传粉者。研究结果显示:白花野牡丹花粉是传粉昆虫的惟一报酬;各传粉昆虫的访花行为与白花野牡丹的开花进程密切相关,因此,可以有效保证白花野牡丹的繁殖。

In order to understand flowering process, floral morphology, type and behavior. of flower visiting insects of Melastoma candidum f. albiflorum J. C. Ou, flowering stage of M. candidum f. albiflorum cultivated in Fairy Lake Botanical Garden of Shenzhen and Chinese Academy of Sciences was observed and statistic analyzed in 2011 and 2012, respectively. The results show that florescence of its single flower is about 12 h, pistil stigmas extend from upcoming opening buds at 7:00, flowers open half at about 8:00, petals fully open at about 8:30 and become close at about 16:00, completely close at about 19:00, petals are no longer opening in the next day and wilt gradually, flowers fall completely until the 4th day. Inflorescence of M. candidum f. albiflorum is subcapitate corymb, each inflorescence has 3-8 flowers; one pistil; two rounds stamens (5+5, 6+6), stamens on inner round are short, while those on outer round are long; non secret nectar. There are 13 flower visiting insects belonging to 5 families in 2 orders at flowering stage of M. candidum f. albiflorum, in which, pollinating insects are 6 species in 2 families, including Xylocopa collaris Lepeletier, Amegilla (Zonamegilla) parhypate Lieftinck, Nomia chalybeata Smith, Nomia sp., Apis cerana cerana Fabricius and Pithitis smaragdula Smith. Flower visiting behavior, flower visiting rule and pollinating efficiency of these 6 pollinating insects are different.In which, daily action rules of X. collaris, A. (Zonamegilla) parhypate, A. cerana cerana and P. smaragdula are single peak type, their peaks of visiting flowers all are at 10:00 or 11:00, while those of N. chalybeata and Nomia sp. are double peak type, their two peaks of visiting flowers are at 10:00 and 15:00, respectively. When petals start to loose, A. cerana cerana and P. smaragdula with small size start to pollinate; with petals opening continually, N. chalybeata and Nomia sp. with medium size are main pollinators, and after petals fully opening, X. collaris and A. (Zonamegilla) parhypate with big size are main pollinators. It is concluded that pollen of M. candidum f. albiflorum is only reward to pollinating insects. Flower visiting behaviors of different pollinating insects are closely related to flowering process of M. candidum f. albiflorum, which can effectively ensure its propagation.