Ferns are primitive vascular plants with diverse morphologies and structures. Plant anatomical traits and their linkages can reflect adaptation to the environment; however, these remain are still poorly understood in ferns. The main objective of this study was to explore whether there was structural coordination among and within organs in fern species. We measured 16 hydraulically related anatomical traits of pinnae, petioles, and roots of 24 representative fern species from the tropical and subtropical forest understory and analyzed trait correlation networks. In addition, we examined phylogenetic signals for the anatomical traits and analyzed co‐evolutionary relationships. These results indicated that stomatal density and all petiole anatomical traits exhibited significant phylogenetic signals. Evolutionary correlations were observed between the tracheid diameter and wall thickness of the petiole and between the water transport capacity of the petiole and stomatal density. Conversely, anatomical traits of roots (e.g., root diameter) showed no phylogenetic signals and were not significantly correlated with those of the pinnae and petioles, indicating a lack of structural coordination between the below‐ and above‐ground organs. Unlike angiosperms, vein density is unrelated to stomatal density or pinna thickness in ferns. As root diameter decreased, the cortex‐to‐stele diameter ratio decreased significantly (enhanced water absorption) in angiosperms but remained unchanged in ferns. These differences lead to different responses of ferns to climate change and improve our knowledge of the water adaptation strategies of ferns.

中文翻译：

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24种热带-亚热带蕨类植物的羽片、叶柄和根部解剖学特征的协调

蕨类植物是原始维管植物，具有多种形态和结构。植物解剖性状及其联系可以反映对环境的适应；然而，对于蕨类植物中的这些仍然知之甚少。本研究的主要目的是探讨蕨类植物器官之间和器官内部是否存在结构协调。我们测量了热带和亚热带森林林下 24 种代表性蕨类植物的羽片、叶柄和根部的 16 个与水力相关的解剖特征，并分析了特征相关网络。此外，我们检查了解剖特征的系统发育信号并分析了共同进化关系。这些结果表明气孔密度和所有叶柄解剖特征表现出显着的系统发育信号。观察了管胞直径和叶柄壁厚之间以及叶柄的水输送能力和气孔密度之间的进化相关性。相反，根的解剖特征（例如根直径）没有显示系统发育信号，并且与羽片和叶柄的解剖特征没有显着相关，表明地下和地上器官之间缺乏结构协调。与被子植物不同，蕨类植物的静脉密度与气孔密度或羽片厚度无关。随着根直径的减小，被子植物的皮层与中柱的直径比显着减小（吸水性增强），但蕨类植物的皮层与中柱直径比保持不变。这些差异导致蕨类植物对气候变化的不同反应，提高了我们对蕨类植物水适应策略的认识。