中文摘要：

假弱楔叶（Sphenophyllum pseudotenerrimum Sze）最早由斯行健于1936年依据江苏无锡上泥盆统五通组的标本建立,后续亦发现于其他产地如浙江、安徽等地区的晚泥盆世地层中。基于浙江长兴五通组的丰富化石,本文对假弱楔叶营养部分的形态学特征和个体发育进行了详细研究。该植物具有至少两级分枝,每级枝均具节与节间,表面具刺和纵肋。二级枝对生或单生于节部。叶轮生于节上,每轮可能有6枚叶,叶长6—18mm,3至4次等二歧式分叉,裂片为线形。发育早期阶段的二级枝节间极短,多轮叶子密集排布。对其分枝宽度与节间长度的统计分析表明,假弱楔叶的个体发育方式可能与石炭纪的楔叶属及现生木贼类相近,存在居间生长。随着植物的生长发育,居间分生组织的活动使得节间长度增加,其分枝长度也随之增长,而在此过程中,节间的数目不再增加或无明显增加。依据新材料,对假弱楔叶营养部分的形态进行了复原,认为植物体低矮,叶形稳定,可能不具异形叶性。

英文摘要：

Sphenophyllurn pseudotenerrimum Sze was established by H. C. Sze in 1936, based on specimens from the Wutong （Wutung） Formation of Wuxi, Jiangsu Province, and later, was also found from the Upper Devonian of Zhejiang and Anhui provinces. Based on newly collected material from the Wutong Formation of Changxing, Zhejiang Province, morphological characters and ontogeny of vegetative parts of S. pseudotenerrirnurn are studied in this paper. This plant has at least two orders of axes, which are characterized by alternation of nodes and internodes and have spines on the surface. Second-order axes are borne oppositely or singly at the node of first-order axes. Leaves, 6-18 mm long, are borne on the node as a whorl, possibly six per whorl, and they are dichotomously di- vided three to four times forming linear divisions. Some second-order axes have very short internodes, as interpreted to be in the early stage of development （immature）, and have densely arranged leaf whorls. Morphometric analysis indicates that S. pseudotenerrimurn probably has intercalary growth that is similar to the Carboniferous Sphenophyllum and the extant genus Equisetum. For the development of this plant, the activities of intercalary meristems will make the internode length extended, and by this way the axis length increases, while the internode number shows no or little changes. Based on our new material, Sphenophyllure pseudotenerrimurn is reconstructed as a small plant with stable leaf morphology and probably, is homophyllous, having leaves of all the same type.