Ryberg Patricia E, Hermsen Elizabeth J, Taylor Edith L, Taylor Thomas N, Osborn Jeffrey M
University of Kansas, Department of Ecology and Evolutionary Biology and Natural History Museum and Biodiversity Research Center, Lawrence, Kansas 66045 USA.
Am J Bot. 2008 Nov;95(11):1443-53. doi: 10.3732/ajb.0800215.
Spaciinodum collinsonii, a Triassic sphenophyte from the central Transantarctic Mountains, Antarctica, is reinterpreted based on new material in order to clarify discrepancies from previous work and to detail the development and ecology of the Spaciinodum plant. Vegetative stems have alternating nodes and internodes, nodes distinguished by a solid diaphragm of tissue, internodes by the presence of vallecular (cortical) and carinal canals, and a hollow pith. Whorls of branches arise immediately above the nodes, alternating with the leaves of the subjacent nodes. Branches develop in the cortex and are anatomically similar to the stems. While Spaciinodum is similar to extant Equisetum, it is distinctive in that its large vallecular canals form a complete ring within the cortex and are separated only by thin fimbrils of tissue. The majority of specimens of Spaciinodum are now believed to be dormant buds with condensed nodes and internodes, with progressively longer internodal regions more basally. More apical portions of buds have cellular internodes because the areas where the canals will form have not yet ruptured from elongation. The abundance of buds and the absence of elongated stems in the permineralized peat deposit suggest that Spaciinodum underwent dormancy during the dark Antarctic winters.
柯林森氏空节木贼（Spaciinodum collinsonii）是一种来自南极洲横贯南极山脉中部的三叠纪楔叶植物，基于新材料对其进行了重新阐释，以厘清与先前研究的差异，并详述空节木贼植物的发育和生态。营养茎具有相间的节和节间，节由坚实的组织隔膜区分，节间则有沟状（皮层）和脊状管道以及中空的髓。枝轮在节的上方紧邻处生出，与下方节的叶交替排列。枝在皮层中发育，在解剖结构上与茎相似。虽然空节木贼与现存的木贼属植物相似，但其独特之处在于其大的沟状管道在皮层内形成一个完整的环，仅由薄的组织纤维分隔。现在认为，空节木贼的大多数标本是具有压缩节和节间的休眠芽，节间区域越靠基部则越长。芽的更顶端部分具有细胞性节间，因为管道将要形成的区域尚未因伸长而破裂。在矿化泥炭沉积物中芽的丰富以及伸长茎的缺失表明，空节木贼在南极黑暗的冬季进入了休眠状态。
