Data from: New insights into floral morph variation in Passiflora incarnata L. (Passifloraceae) in Tennessee, U.S.A.

Passiflora incarnata is a functionally andromonoecious clonal wildflower, native to the southeastern United States, whose primary pollinator is the carpenter bee, Xylocopa virginica. While recent studies looking at reproductive ecology in P. incarnata have classified flowers as one of two morphs (male or hermaphroditic) based on stylar deflexion, preliminary field studies conducted in Tennessee indicated there were five distinct morphs present (three male, two hermaphroditic), supported by stylar deflexion, floral size, and pistil development. The present study sought to test the hypothesis that five distinct floral morphs are present in P. incarnata by sampling 13 floral characters, and to document variation in nectar constituents, volume, and concentration across the five morphs. Five well-established individual plants were examined at three sites in Cookeville, Tennessee. Two-factor permuted analysis of variance of 13 floral characteristics with floral morph and individual plants as factors suggested that morph:plant interactions explained 6%, individual plant explained 18%, and floral morph explained 36% of variation in floral characteristics. Nectar sampling indicated that all morphs produced nectar comprised exclusively of sucrose. Nectar volume generally increased with floral morph size, while nectar concentration decreased. NMDS analysis indicated that the five hypothesized morphs were supported as distinct, with substantial overlap between the two largest morphs (4a and 4b). The supported morphs are best distinguished by ovary width, ovary length, style length, and stigma width. These findings support a hypothesis that the morphs result from variation in developmental arrest during floral ontogeny. The ecological implications of the five morphs and nectar variation are considered for X. virginica with suggestions for additional studies.

红花西番莲（Passiflora incarnata）是一种功能性雄全同株（andromonoecious）的克隆（clonal）野生花卉，原产于美国东南部，其主要传粉者为弗吉尼亚木蜂（Xylocopa virginica）。此前针对红花西番莲繁殖生态学的研究多根据花柱反折（stylar deflexion）特征将其花朵划分为雄花、两性花（hermaphroditic）两种花型，但在田纳西州开展的初步野外调查显示，当地存在5种独立的花型（3种雄花、2种两性花），该结论得到了花柱反折、花部大小以及雌蕊发育状态的支撑。本研究通过采集13个花部性状（floral characters）数据，旨在验证红花西番莲存在5种独立花型的假说，并记录5种花型的花蜜成分、体积及浓度差异，研究在田纳西州库克维尔的3个样地选取了5株生长状态稳定的个体进行观测。以花型和个体植株为因素，对13个花部性状开展双因素置换方差分析（permuted analysis of variance），结果显示花型与植株的交互作用可解释6%的花部性状变异，植株个体可解释18%，而花型本身可解释36%的变异。花蜜采样分析表明，所有花型的花蜜均仅由蔗糖构成，花蜜体积通常随花型尺寸增大而升高，而花蜜浓度则随之降低。非度量多维尺度分析（NMDS, Non-metric Multidimensional Scaling）结果显示，5种假说中的花型均为独立类群，其中体型最大的两种花型（4a与4b）之间存在显著重叠，可通过子房宽度、子房长度、花柱长度以及柱头宽度这几个性状对确认的5种花型实现最佳区分。上述研究结果支撑了"花型差异源于花部个体发育（floral ontogeny）过程中不同程度的发育停滞（developmental arrest）"这一假说，本研究还探讨了5种花型及花蜜性状差异对弗吉尼亚木蜂的生态学意义，并提出了后续研究的建议。