Numerous anatomically preserved fragments of the Middle Pennsylvanian age filicalean fern, Botryopteris tridentata, occur in coal balls collected at the Pittsburgh and Midway Coal Company mine near Baxter Springs, Kansas. Included are the first fertile specimens of the species, evidence of complete vegetative frond architecture, and fronds that are specialized for vegetative propagation. Rhizomes are erect and unbranched, have helical phyllotaxis and short internodes, and typically display an ectophloic solenostele. Fronds are tripinnately compound with lobed pinnules that have open, dichotomous venation. Fertile pinnae or individual pinnules are interspersed among vegetative frond segments and produce sori of annulate sporangia beneath veins on the abaxial pinnule surface. Fertile pinnule lobes are rolled toward the abaxial surface to enclose the sori. Sporangia have a horizontally elongated biseriate annulus located near the short broad stalk and produce tetrahedral‐shaped trilete spores with coarse spines. Epiphyllous branches diverge from the stipe or rachis, and some fronds produce only branches. This fern is reconstructed as having short stems. Helically arranged fronds are either pinnately dissected with lobed vegetative pinnules and abaxially rolled fertile pinnules or are specialized for vegetative propagation. The latter functioned as the foliar equivalent of stolons. While some characters of the B. tridentata plant are similar to those of Botryopteris forensis, generitype of the Botryopteridaceae, others are more comparable to those of Psalixochlaena cylindrica, generitype of Psalixochlaenaceae, suggesting the need for reevaluation of systematic relationships among species of the Botryopteridaceae and Psalixochlaenaceae.

中文翻译：

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重建宾夕法尼亚时代的 Filicalean FernBotryopteris tridentata(Felix) Scott

在堪萨斯州巴克斯特斯普林斯附近的匹兹堡和中途煤炭公司煤矿收集的煤球中，发现了许多解剖学上保存完好的宾夕法尼亚州中叶蕨类植物 Botryopteris tridentata 碎片。包括该物种的第一个可育标本、完整营养叶结构的证据以及专门用于营养繁殖的叶。根状茎直立且不分枝，具有螺旋状的叶序和短节间，并且通常显示出外生的柱状茎。叶是三瓣复叶，具有开放的二分脉的裂片羽叶。可育的羽片或单个羽片散布在营养叶片之间，并在背面羽片表面的脉下产生环状孢子囊。肥沃的羽片叶被卷向背面以包围sori。孢子囊有一个水平拉长的双列环，位于短而宽的茎附近，产生四面体形的三列孢子和粗刺。叶生分枝从叶柄或轴分出，有些叶只产生分枝。这种蕨类植物被重建为具有短茎。螺旋状排列的叶状体要么羽状地解剖成有叶的营养小羽片和背面卷曲的可育小羽片，要么专门用于营养繁殖。后者作为匍匐茎的叶面等效物。虽然 B. tridentata 植物的某些性状与 Botryopteris forensis（Botryopteridaceae 属的 Botryopteris forensis）相似，但其他一些性状与 Psalixochlaena cylindrica（Psalixochlaenaceae 的属型）更相似，