Abstract Intraspecific variability of anatomical leaf traits is usually determined on the basis of median sections and interpreted as adaptive. We hypothesized that anatomical traits may relate to the position within the leaf, reflecting functional coordination e.g., between transport and gas exchange capacities and between supporting tissue and the supported leaf weight. Anatomical variation may thus be partly controlled by leaf size. We examined variability of transverse anatomical traits and stomata at different positions along the leaf axis using Scots pine (Pinus sylvestris L.) needles collected from three geographical locations with contrasting climate (Poland, Southern and Northern Sweden) and differing in length. Transverse xylem and phloem area, and the number of tracheids at a given cross-section scaled positively with length of the distal needle part and the number of distal stomata. Similarly, the number of vascular sclerenchyma fibers in a cross-section scaled with the length and volume of the distal needle part. Allometric slopes were less steep in the longer, southern-sites needles. Additionally, our study revealed an increased sclerification of epidermis towards the needle apex, the occurrence of widest tracheids in central or subapical regions, a reduced number of resin ducts in basal and apical parts, as well as overall basipetal decreases in duct diameter, the number of stomatal files and stomatal density. These results show that allometry accounts for significant amount of intraspecific variability in xylem, phloem and fibers, and that environmental adaptation involves also modification of the within-needle allometric relationships. The allometric component of variability, together with the nonlinear distribution of certain traits along needle length, should be considered when designing comparative studies of foliar phenotypes and scaling up from transverse sections to entire needles.

中文翻译：

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解剖结构的轴向变异性和不同起源的苏格兰松 (Pinus sylvestris L.) 针叶的缩放关系

摘要 解剖叶片性状的种内变异通常是根据中位数确定的，并解释为适应性。我们假设解剖特征可能与叶片内的位置有关，反映了功能协调，例如，运输和气体交换能力之间以及支撑组织和支撑叶片重量之间的协调。因此，解剖变异可以部分地由叶片大小控制。我们使用从气候截然不同的三个地理位置（波兰、瑞典南部和瑞典北部）和长度不同的苏格兰松（Pinus sylvestris L.）针叶检测了沿叶轴不同位置的横向解剖特征和气孔的变异性。横向木质部和韧皮部区域，并且在给定横截面的气胞数量与远端针部分的长度和远端气孔的数量成正比。类似地，横截面中血管厚壁组织纤维的数量与远端针部分的长度和体积成比例。在较长的南部地点的针叶中，异速生长的斜坡不那么陡峭。此外，我们的研究表明，表皮朝向针尖的硬化增加，中心或尖下区域出现最宽的气管，基底和顶端部分的树脂导管数量减少，以及导管直径的整体基叶减少，数量气孔文件和气孔密度。这些结果表明异速生长解释了木质部、韧皮部和纤维的大量种内变异，并且环境适应还涉及针内异速生长关系的修改。在设计叶表型的比较研究和从横切面扩大到整个针叶时，应考虑变异性的异速生长成分以及某些性状沿针叶长度的非线性分布。