Abstract A new whole-plant species of a calamitacean, Palaeostachya guanglongii sp. nov., is described in a volcanic ash bed from the Cisuralian (lower Permian) Wuda Coalfield, Inner Mongolia, North China. It was an approximately 2–3 m high shrub-like plant growing in a peat-forming swamp. It is characterized by three-orders of axes. The stem (first-order axis) bifurcates, resulting in two equal-sized major branches (second-order axis); both axial orders conform to the morphotaxon Calamites cf. schutzeiformis type with Arthropitys type anatomy. Each major branch bears numerous ultimate branches that are composed of vegetative and fertile branches. Vegetative branches bear the leaf Asterophyllites longifolius, while fertile branches bear A. longifolius leaves at proximal nodes and P. guanglongii sp. nov. strobili at distal nodes. Whorls of bracts and sporangiophores alternate in the strobili, with sporangiophores inserting slightly above the bract whorls. Four sporangiophores make up one whorl, with each sporangiophore bearing four sporangia, yielding in situ spores of the Calamospora type. The bifurcating stem is unique in Sphenopsida, potentially indicating the development of determinate branching in this group. Our findings also extend the knowledge of the morphological plasticity of a combination of anatomical features of the wood and interfascicular.

中文翻译：

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内蒙古乌达煤田阿瑟连（二叠系）太原组一株菖蒲古龙骨全株

摘要 菖蒲科全草新种Palaeoostachya guanglongii sp。11 月，描述于华北内蒙古 Cisuralian（下二叠统）乌达煤田的火山灰层中。它是一种生长在泥炭沼泽中的大约 2-3 m 高的灌木状植物。它的特点是三阶轴。茎（一阶轴）分叉，产生两个大小相等的主枝（二阶轴）；两个轴向顺序都符合 morphotaxon Calamites cf。schutzeiformis 型与关节型解剖学。每个主要分支都有许多最终分支，由营养分支和可育分支组成。营养枝上有叶星形石长叶，而肥沃的枝在近节上有长叶 A. longifolius 叶和 P. guanglongii sp。十一月 strobili 在远端节点。苞片的轮生和孢子囊在strobili 中交替，孢子囊插入在苞片轮稍上方。四个孢子囊构成一个螺旋体，每个孢囊体带有四个孢子囊，产生 Calamospora 类型的原位孢子。分叉茎在 Sphenopsida 中是独一无二的，这可能表明该组中确定分枝的发展。我们的发现还扩展了对木材和束间解剖特征组合的形态可塑性的认识。可能表明该组中确定分支的发展。我们的发现还扩展了对木材和束间解剖特征组合的形态可塑性的认识。可能表明该组中确定分支的发展。我们的发现还扩展了对木材和束间解剖特征组合的形态可塑性的认识。