摘要
本文对斜方薄皮木(Leptophloeum rhombicum)的维管组织作了解剖学方面的新观察。在木质部中,次生木质部细胞结构没有保存,仅见在初生木质部外围留下了放射状条痕。初生木质部呈实心的圆柱状,外始式,周边具纵脊;后生木质部均由梯状分子构成,在相邻的梯棒之间具威廉森纹,根据该纹的形态和它与梯棒的连接关系,它被认为属于次生加厚的一部分。综合前人的工作和本文观察的结果,斜方薄皮木极可能是鳞木目的成员。
A petrified stem of Leptophloeum rhombicum is described from the Huangjiadeng Form- ation of the Upper Devonian in Changyang,Hubei.In the xylem of the axis,the secondary xy- lem is not preserved,the greatest part of the primary xylem is composed of metaxylem tracheids that are scalariform and have Williamson's striations.Based on their connections between adj- acent transverse bars Williamson's striations would be considered as a part of the secondary wall material.The small protoxylem tracheids form vertical ridges at the periphery of primary xylem cylinder.In cross section,the ridges appear as small radiating teeth of protoxylem.It provides further evidence that primary xylem in Leptophloeum rhombicum is similar to that in Carboniferous lepidodendrid lycopods.The opinion that the systematic position of Lepto- phloeum should be transferred from the Protolepidodendrales to the Lepidodendrales could be accepted and reaffirmed.
基金
国家自然科学基金
关键词
斜方薄皮木
泥盆世
湖北
Leptophloeum rhombicum
Primary xylem
Williamson's striation
Lepidodendrales
