Abstract Leaves are the main photosynthetic organs of plants. There is almost an infinite variety of leaf shapes and venations. The purpose of the current study was to determine if leaf areas, leaf veins and xylem conductivities are well scaled among primary, secondary and tertiary tiers in leaves with percurrent leaf venation for 32 species. Data from both fully-expanded leaves and leaves that underwent expansion were analyzed. Thirty-two species with leaves of 7.25 to 887 cm2 lamina areas with a median leaf area of 81 cm2 were tested. On average, leaves had 19 secondary veins 45 mm long to produce secondary areas of 4.1 cm2. Leaves had 272 tertiary areas, each 0.30 cm2, in which the median tertiary veins were 10 mm in length. There were strong relationships between lamina areas, vein lengths, vessel numbers, vessel radii and xylem conductivities among tier levels. Primary veins had a median xylem conductivity of 1.02 g cm-1 MPa-1 s-1 while secondary and tertiary xylem conductivities were 0.51 and 0.00081 g cm-1 MPa-1 s-1, respectively. The above strong relationships for fully-expanded leaves were confirmed for five species during leaf expansion. Estimates of water conduction with respect to lamina areas, vein characteristics and xylem conductivities among tier levels are presented. The strong relationships among the above parameters of this study suggest that leaf characteristics of leaf lamina areas, veins lengths and xylem conductivities of each species are well scaled to provide water to all areas of leaves.

中文翻译：

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叶脉中的木质部电导率

摘要 叶子是植物的主要光合器官。几乎有无数种叶子形状和脉络。当前研究的目的是确定叶面积、叶脉和木质部电导率是否在具有 percurrent 叶脉的 32 个物种的叶片中的初级、二级和三级之间良好地缩放。分析了来自完全展开的叶子和经历展开的叶子的数据。测试了叶面积为 7.25 至 887 平方厘米、叶面积中位数为 81 平方厘米的 32 个物种。平均而言，叶子有 19 条 45 毫米长的次生脉，产生 4.1 平方厘米的次生面积。叶有 272 个三级区域，每个区域 0.30 cm2，其中三级脉的中间长度为 10 mm。椎板面积、静脉长度、血管数量、层级之间的容器半径和木质部电导率。初级静脉的木质部电导率中值为 1.02 g cm-1 MPa-1 s-1，而二级和三级木质部电导率分别为 0.51 和 0.00081 g cm-1 MPa-1 s-1。在叶片扩张过程中，五个物种证实了上述完全扩张叶片的强关系。呈现了层级之间关于叶片面积、静脉特征和木质部传导率的水传导估计。本研究的上述参数之间的密切关系表明，每个物种的叶片面积、叶脉长度和木质部传导率的叶片特征都经过很好的调整，可以为叶片的所有区域提供水分。02 g cm-1 MPa-1 s-1 而二级和三级木质部的电导率分别为 0.51 和 0.00081 g cm-1 MPa-1 s-1。在叶片扩张过程中，五个物种证实了上述完全扩张叶片的强关系。呈现了层级之间关于叶片面积、静脉特征和木质部传导率的水传导估计。本研究的上述参数之间的密切关系表明，每个物种的叶片面积、叶脉长度和木质部传导率的叶片特征都经过很好的调整，可以为叶片的所有区域提供水分。02 g cm-1 MPa-1 s-1 而二级和三级木质部的电导率分别为 0.51 和 0.00081 g cm-1 MPa-1 s-1。在叶片扩张过程中，五个物种证实了上述完全扩张叶片的强关系。呈现了层级之间关于叶片面积、静脉特征和木质部传导率的水传导估计。本研究的上述参数之间的密切关系表明，每个物种的叶片面积、叶脉长度和木质部传导率的叶片特征都经过很好的调整，可以为叶片的所有区域提供水分。呈现了层级之间的静脉特征和木质部电导率。本研究的上述参数之间的密切关系表明，每个物种的叶片面积、叶脉长度和木质部传导率的叶片特征都经过很好的调整，可以为叶片的所有区域提供水分。呈现了层级之间的静脉特征和木质部电导率。本研究的上述参数之间的密切关系表明，每个物种的叶片面积、叶脉长度和木质部传导率的叶片特征都经过很好的调整，可以为叶片的所有区域提供水分。