Osborn JM, Phipps CJ, Taylor TN, Taylor EL
Division of Science, Truman State University, 63501, Kirksville, MO, USA
Rev Palaeobot Palynol. 2000 Sep 1;111(3-4):225-235. doi: 10.1016/s0034-6667(00)00026-9.
Permineralized cones found organically attached to Spaciinodum collinsonii stems are described from the early Middle Triassic silicified flora from the Fremouw Formation of Antarctica, and the species diagnosis is emended to include the reproductive specimens. The apical cones are organized into internodal and leaf-bearing nodal regions. Nodal septations span the central pith and cortex, and thin fimbrils subdivide the internodal areas into smaller chambers. The vascular system consists of 31-33 continuous bundles that do not alternate in position between successive nodes and internodes. Simple sporangia are associated with the cortical chambers and occur in one whorl on the axis. Spores are small, lack elaters, and have no discernible ultrastructure preserved, and they are interpreted to be immature. The Antarctic cones are different in structure from typical cones of modern and fossil members of Equisetales; however, they share similarities with some morphologically aberrant cones of extant Equisetum and several Late Paleozoic and Mesozoic compression-impression fossils. Spaciinodum is now the most complete anatomically described Mesozoic sphenophyte.
在南极洲弗勒莫组早三叠世硅化植物群中发现了与科林森氏空间节蕨茎有机相连的矿化锥体，并且对该物种的诊断进行了修订，将生殖标本纳入其中。顶端锥体由节间区域和着叶的节区域组成。节间隔横跨中央髓和皮层，细纤维将节间区域细分为更小的腔室。维管系统由31 - 33个连续的维管束组成，这些维管束在连续的节和节间之间位置不交替。简单的孢子囊与皮层腔室相关，在轴上呈一轮排列。孢子很小，没有弹丝，也没有保存下来可辨别的超微结构，被解释为未成熟状态。南极锥体在结构上与现代和化石木贼目的典型锥体不同；然而，它们与现存木贼属一些形态异常的锥体以及一些晚古生代和中生代压型化石有相似之处。空间节蕨现在是解剖学描述最完整的中生代楔叶植物。
