Using 227 dicotyledonous species in temperate region, we found the relationships among densities of different-order veins, creating diversity of leaf vascular architectures. Dicotyledonous angiosperms commonly possess a hierarchical leaf vascular system, wherein veins of different orders have different functions. Minor vein spacing determines leaf hydraulic efficiency, whereas the major veins provide mechanical support. However, there is limited information on the coordination between these vein orders across species, limiting our understanding of how diversity in vein architecture is arrayed. We aimed to examine the (1) relationships between vein densities at two spatial scales (lower- vs. higher-order veins and among minor veins) and (2) relationships of vein densities with plant functional traits. We studied ten traits related to vein densities and three functional traits (leaf dry mass per area [LMA], leaf longevity [LL], and adult plant height [Hadult]) for 227 phylogenetically diverse plant species that occur in temperate regions and examined the vein–vein and vein–functional traits relationships across species. The densities of lower- and higher-order veins were positively correlated across species. The minor vein density was positively correlated with the densities of both areoles and free-ending veins, and vascular networks with higher minor vein density tended to have a lower ratio of free-ending veins to areoles across species. Neither densities of lower- nor higher-order veins were related to LMA and LL. On the other hand, the densities of veins and areoles tended to be positively correlated with Hadult. These results suggest that densities of different-order veins are developmentally coordinated across dicotyledonous angiosperms and form the independent axis in resource use strategies based on the leaf economics spectrum.

中文翻译：

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温带双子叶植物的叶维管结构：与功能性状的相关性和联系

使用温带地区的 227 个双子叶植物，我们发现了不同阶脉密度之间的关系，创造了叶维管结构的多样性。双子叶被子植物通常具有分层的叶维管系统，其中不同顺序的叶脉具有不同的功能。小叶脉间距决定叶片水力效率，而大叶脉提供机械支撑。然而，关于跨物种的这些脉序之间协调的信息有限，限制了我们对脉结构多样性如何排列的理解。我们的目的是检查（1）两个空间尺度（低级与高级静脉和次要静脉之间）的静脉密度之间的关系和（2）静脉密度与植物功能性状的关系。我们研究了 10 个与叶脉密度相关的性状和 3 个功能性状（单位面积叶干质量 [LMA]、叶寿命 [LL] 和成株高度 [Hadult]），研究了温带地区 227 种系统发育多样的植物物种，并检查了跨物种的静脉 - 静脉和静脉 - 功能性状关系。低阶和高阶静脉的密度在物种之间呈正相关。小静脉密度与小静脉和自由端静脉的密度呈正相关，小静脉密度较高的血管网络在不同物种中往往具有较低的自由端静脉与小静脉的比率。低阶或高阶静脉的密度均与 LMA 和 LL 无关。另一方面，静脉和乳晕的密度往往与 Hadult 呈正相关。