Specialised emission pattern of leaf trace in a late Permian (253 million-years old) conifer.
Specialised emission pattern of leaf trace in a late Permian (253 million-years old) conifer.
复制标题
二叠纪晚期（2.53 亿年）针叶树叶迹的特殊发射模式
DOI：
10.1038/srep12405
复制
发表时间：
2015-07-22
影响因子：
4.6
通讯作者：
He XY
中科院分区：
文献类型：
--
作者：
Wei HB;Feng Z;Yang JY;Chen YX;Shen JJ;He XY
叶迹是高等植物中连接叶片和茎维管系统的重要结构。叶痕迹的解剖和发射模式在现存的维管植物中得到了很好的研究，但在化石谱系中仍然知之甚少。本文通过髓、原生、次生木质部连续切片，定量分析了中国西北部晚二叠世针叶植物宁夏特产的叶迹。首次给出了晚古生代以来针叶树完整的叶迹发射模式。三到五个君主叶迹被聚在一起，以螺旋状的叶序排列。每一簇中的叶迹可分为上、中、下三部分，始于髓周缘，水平穿过木材。上部叶迹在第一次生长期间直径增大，然后完全消失，表明第一年末叶片脱落。中间的痕迹立即分叉一到两次，形成两到三个维管束。较低的轨迹在其整个长度期间作为单个束持续存在。复杂的叶迹动态表明，这种化石植物具有一种新的进化习性，它促进了成熟植物的光合作用能力。
Leaf traces are important structures in higher plants that connect leaves and the stem vascular system. The anatomy and emission pattern of leaf traces are well studied in extant vascular plants, but remain poorly understood in fossil lineages. We quantitatively analysed the leaf traces in the late Permian coniferNingxiaites specialisfrom Northwest China based on serial sections through pith, primary and secondary xylems. A complete leaf traces emission pattern of a conifer is presented for the first time from the late Palaeozoic. Three to five monarch leaf traces are grouped in clusters, arranged in a helical phyllotaxis. The leaf traces in each cluster can be divided into upper, middle and lower portions and initiate at the pith periphery and cross the wood horizontally. The upper leaf trace increases its diameter during the first growth increment and then diminishes completely, which indicates leaf abscission at the end of the first year. The middle trace immediately bifurcates once or twice to form two or three vascular bundles. The lower trace persists as a single bundle during its entire length. The intricate leaf trace dynamics indicates this fossil plant had a novel evolutionary habit by promoting photosynthetic capability for the matured plant.