Cycad wood from the Lopingian (Late Permian) of southern China:Shuichengoxylon tianii gen. et sp. nov.
作 者：Shi-Jun Wang, Xiao-Yuan He, Long-Yi Shao
影响因子：2.364
刊物名称：International Journal of Plant Sciences
出版年份：May-2011
卷：172 期：5 页码：725-734
论文摘要：
Anatomically preserved wood collected from coal seam no. 1 of the Naluozhai coal mine in the Lopingian (Late Permian) Wangjiazhai Formation in western Guizhou Province, China, is documented and interpreted. The wood belonged to a trunk with an inferred diameter of 25 cm or more and consists of axial tracheids and horizontal rays. Tracheids vary greatly in size, and small ones are usually irregularly arranged. Tracheid walls are 5–10 mm thick and usually bilayered. There are usually biseriate araucarioides-type bordered pits on the radial tracheid walls. Two to five oval bordered pits are in each cross-field. Ray cells are thin walled, although thick-walled cells exist in some rays. Rays are quite variable in width and height. Uni- and partly biseriate rays are usually 2–20 cells high, while bi- and partly tri- to tetraseriate ones are 5–79 cells high. The cell size of rays is also quite variable and is usually larger than that of tracheids in the tangential direction. There are numerous leaf traces in the wood, and each of them extends horizontally through the wood within a broader ray. The last character is unique in known Paleozoic woods and leads to the establishment of Shuichengoxylon tianii gen. et sp. nov. The affinity of the wood with cycads, its implication in the evolution of cycad xylotomy, and its growth environment are discussed.
