The species-rich flora of Madagascar is well known for a range of unusual floral ecologies. One example is Impatiens section Trimorphopetalum with its unique combination of floral traits: small, spur-less, cup- or lip-shaped, greenish or brownish flowers. So far no hypotheses on floral function or pollination of this peculiar group have been proposed. We analysed six reproductive traits in relation to pollination syndromes for 34 Madagascan Impatiens species, including 18 species of section Trimorphopetalum plus six outgroup species, in a phylogenetic framework. Further, we present pollinator observations for one additional species of Trimophopetalum. All pollination syndromes occurring in the African species are also present in Madagascan Impatiens. In addition, species of Trimorphopetalum represent two unique floral types, possibly corresponding to two different types of fly pollination. The evolution of these flower types corresponds to a strong decrease in nectar production, flower display size, pollen grain and ovule number. Autogamy is found in one derived sub-clade of the otherwise largely pollinator-dependent Trimorphopetalum. We find evidence consistent with the evolution of brood-site deception and fungus mimicry in combination with fly pollination in one clade of Trimorphopetalum and the stepwise evolution of autogamy in the second clade. The evolution of these very different reproductive strategies may have been triggered by pollinator limitation in the dense, humid forest undergrowth of Madagascar.

马达加斯加物种丰富的植物区系因一系列不同寻常的花卉生态而闻名。一个例子是凤仙花部分的Trimorphopetalum，具有独特的花卉特征组合：小，无刺，杯形或唇形，绿色或棕褐色的花。迄今为止，尚未提出关于该奇特组的花功能或授粉的假设。在系统发育框架中，我们分析了与马达加斯加凤仙花属的34种马达加斯加花粉症候群有关的6个生殖性状，其中包括18种Trimorphopetalum和6种外群种。此外，我们提出了传粉者对另外一种Trimophopetalum物种的观察。在马达加斯加凤仙花中也存在非洲物种中发生的所有授粉综合症。此外，三角花的物种代表两种独特的花卉类型，可能对应于两种不同类型的蝇授粉。这些花类型的演变对应于花蜜产量，花展示尺寸，花粉粒和胚珠数量的强烈减少。在另一种主要依赖传粉媒介的三形morph的衍生子丛中发现了同卵配子。我们发现与一枝三形花果蝇结合授粉和授粉的仿生进化相一致的证据以及第二进化枝中同性婚姻的逐步发展。马达加斯加茂密湿润的森林中授粉媒介的限制可能触发了这些截然不同的繁殖策略的演变。