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.紫花西番莲（Passiflora incarnata）是一种功能性雄全同株的无性系野生花卉，原产于美国东南部，其主要传粉者为弗吉尼亚木蜂（Xylocopa virginica）。近期针对该物种繁殖生态学的研究，依据花柱偏折特征将其花划分为两种形态：雄花与两性花。但此前在田纳西州开展的初步野外调查显示，该物种存在5种不同的花形态（3种雄花、2种两性花），该分类得到了花柱偏折、花部大小以及雌蕊发育状态的佐证。本研究通过对13个花部性状进行取样测定，旨在验证紫花西番莲存在5种花形态这一假说，并系统记录5种花型的花蜜成分、体积与浓度差异。研究团队在田纳西州库克维尔的3个采样点，对5株生长健壮的成熟植株进行了观测。以花型和植株个体为因素，对13个花部性状开展双因素置换方差分析，结果表明：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%的变异，而花型本身可解释36%的变异。花蜜取样测定结果显示，所有花型的花蜜均仅由蔗糖组成。花蜜体积通常随花型增大而升高，而花蜜浓度则随之降低。非度量多维尺度分析（Non-metric Multidimensional Scaling, NMDS）结果证实，5种假说中的花型确实彼此区分，其中两种最大的花型（4a与4b）存在显著重叠。经证实的5种花型，最易通过子房宽度、子房长度、花柱长度以及柱头宽度加以区分。本研究结果支持如下假说：这些花型的差异源于花发育进程中发育停滞程度的差异。本研究还探讨了5种花型与花蜜变异对弗吉尼亚木蜂的生态学意义，并提出了后续研究的方向与建议。