J Integr Plant Biol. ›› 2003, Vol. 45 ›› Issue (1): 15-22.

• Research Articles • Previous Articles     Next Articles

Anatomical Structures of “Lepidodendron” pulchrum Zhang in Coal_balls from the Taiyuan Formation (Lower Lower Permian) in Shandong Province, North China

CHEN Gui-Ren,WANG Shi-Jun,TIAN Bao-Lin   


This study reports the anatomical structures of a kind of lepidodendralean stem in coal balls from the early Early Permian Taiyuan Formation in Yanzhou Mining District, southwestern Shandong Province, North China. The leaf cushion is slightly rhomboid in outline with a height of 9-10 mm and a width of 7.5-9.0 mm and its lower sides are slightly longer than the upper ones. The top and basic angles of the leaf cushion are truncate and the basic angle is slightly elongate. The upper part of the leaf cushion is strongly high_rising. The leaf scar is large and lenticular in shape. The leaf trace is wide and V_shaped in the leaf scar, and horizontally elongate within the leaf cushion. The leaf trace and lateral parichnos strand extend at a nearly horizontal course outward within the leaf cushion. The ligular pit is deep and extends outward at an oblique course and its aperture is located near the top angle of the leaf scar. No infrafoliar parichnos strands are present. The stem is probably siphonostelic and its pith is probably parenchymatous. The primary xylem is exarch with a nearly smooth outer margin. Only the outer cortex is present and it consists of alternately_arranged radial cell bands and gaps within which the arc_shaped or V_shaped leaf traces can be seen. The concave side of the leaf trace is toward the center of the stem. No bundle sheath is developed. Periderm is well_developed and consists of phelloderm and phellem in nearly equal thickness. Compared with the lepidodendralean stems of the Cathaysian and Euramerican Floras, the present specimens are most close to an impression_compression species Lepidodendron pulchrum Zhang in morphology of the leaf cushion and they are put into this species temporarily. Whether the present specimens or the type specimens of L. pulchrum are very different from Lepidodendron Sternburg sensu DiMichele, thus the correct nomenclature and classification of L. pulchrum needs to be reconsidered based on the study of better_ and anatomically_preserved stems and fertile organs in the future. Because “L”. Pulchrum possesses the mixed features of several genera of Euramerican lepidodendralean stems, it bears significance to study the origin and evolution of the Cathaysian lepidodendralean lycopods. Key words: Cathaysian Flora; Early permian; coal balls; “Lepidodendron” pulchrum; stems; anatomy

陈贵仁1 王士俊2* 田宝霖1
(1. 中国矿业大学,北京 100083;2. 中国科学院植物研究所,北京 100093)

摘要: 描述了山东兖州矿区太原组(早二叠世早期)煤核中一种具叶座的鳞木类茎的解剖构造。叶座呈略不对称的菱形,下侧边略长于上侧边,顶、底角均平截,底角并略呈拖延状;叶座上部突起较强烈,叶痕双凸镜形,叶迹呈宽V 字形,叶迹与侧通气束可能都以近水平状在叶座内向外延伸;叶舌穴深,自叶座最内处向外斜伸,开口位于叶痕顶角附近。叶座底部表面具横皱纹。茎可能具管状中柱和薄壁组织的髓。初生木质部外始式,外缘较平滑。仅见有外部皮层,由径向伸长的壁较厚的细胞条带和夹于其间的空腔交替排列构成,空腔内可见弧形或宽b 字形叶迹,其凹面朝向内方。周皮较发育,由近等量发育的木栓层和栓内层组成。经比较,当前标本与华夏植物区的印痕———压型化石种美丽鳞木在叶座的形态上非常相似,暂归入该种。由于无论是当前标本还是美丽鳞木的模式标本与狭义的鳞木属都有很大区别,因此美丽“鳞木”的确切归属还有待于今后进一步对保存更好的具解剖构造的茎和生殖器官的研究。美丽“鳞木”与欧美植物区几个乔木状鳞木类植物属的茎都不完全相同,具有它们的混合特征,很可能代表了一个新属。美丽“鳞木”是目前华夏植物区研究得最详细的一种具解剖构造的鳞木类的茎,对于研究华夏植物区鳞木类植物的起源和演化具有一定的意义。
关键词: 华夏植物群;早二叠世;煤核;美丽“鳞木”;茎;解剖构造

!通讯作者。E-mail: wangsj@ns.ibcas.ac.cn


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