宁夏石炭井孙家沟组特殊宁夏木树皮及叶解剖学初步研究

发布时间：2018-04-18 12:33

本文选题：特殊宁夏木 + 松柏类　；参考：《云南大学》2015年硕士论文

【摘要】：松柏类是晚二叠世的重要植物类群,但对于晚二叠世松柏类植物的认识主要来自于叶部印痕化石的研究,而对其树皮及叶的解剖研究工作相对较少。近年来,随着对晚古生代矿化裸子植物研究的深入,松柏类植物的解剖工作也做得更加详细,其解剖特征不仅提供了重要的分类学信息,还对植物的系统发育和演化历程具有一定的指导意义。本文通过对宁夏石炭井乐平统孙家沟组矿化植物特殊宁夏木(Ningxiaites specialis Feng)的解剖学研究,首次详细描述了华夏植物群晚古生代松柏类植物的树皮和叶的解剖结构。特殊宁夏木保存了精美的木质部外组织,包括维管形成层和树皮。维管形成层由一至两层的纺锤形细胞组成。维管形成层外的树皮保存了次生韧皮部和周皮组织,厚1.8mm。次生韧皮部由筛胞、射线和轴向薄壁细胞组成,分为新的次生韧皮部和老的次生韧皮部。新的次生韧皮部中射线细胞较多,轴向薄壁细胞较少,主要由筛胞带重复排列组成。横切面上,筛胞亚圆形至方形,直径约30μm,筛胞壁厚约2μm。径切面上,筛胞细长呈管柱状,筛胞径向壁上可见近圆形的筛域,呈单列线形排列。韧皮射线与木质射线相连,韧皮部中的射线细胞较木质部射线细胞膨大。老的次生韧皮部中轴向薄壁细胞数量增加,射线细胞减少。周皮由木栓细胞组成,木栓细胞被暗色物质填充,呈覆瓦状排列。特殊宁夏木叶结构包括表皮,叶肉组织和维管组织。叶螺旋着生于轴上,横切面上,叶呈半圆形、梯形或三角形。表皮细胞一层,排列紧密,表皮外覆盖有发达的角质层,角质层中有圆柱形或条形乳状突起。叶肉细胞分化成栅栏组织和海绵组织。在叶表皮上具有明显的气孔带,气孔带平行纵向排列；气孔器由一对肾形保卫细胞和周围的副卫细胞环绕组成。内皮层由一层薄壁细胞组成,包裹着维管组织,维管组织包括维管束和转输细胞。叶具一条维管束,不分叉；转输细胞多边形,细胞壁上具纹孔。树脂道缺失。
[Abstract]:Pine cypress is an important plant group of late Permian, but the understanding of late Permian pine and cypress comes mainly from the study of leaf imprint fossils, but there is relatively little research on its bark and leaf anatomy.In recent years, with the further study of late Paleozoic mineralized gymnosperms, the anatomical work of pine and cypress plants has been done in more detail, whose anatomical characteristics not only provide important taxonomic information.It is also helpful to the phylogeny and evolution of plants.Based on the anatomical study on the special mineralized plants of the Sunjiagou formation of the Leping series in Liuping formation, Ningxia, the bark and leaf anatomical structure of the late Paleozoic pine cypress in the Huaxia flora was described in detail for the first time in this paper.Special Ningxia wood preserved fine xylem outer tissue, including vascular cambium and bark.Vascular cambium consists of one or two layers of spindle cells.The bark outside the vascular cambium preserved the secondary phloem and pericarp tissues with a thickness of 1.8 mm.The secondary phloem is composed of ethmoid, ray and axial parenchyma cells, and is divided into new secondary phloem and old secondary phloem.In the new secondary phloem, there were more ray cells and less axonal parenchyma cells, which were mainly composed of sieve cell bands.On the cross section, the ethmoid was subcircular to square, about 30 渭 m in diameter and 2 渭 m in thickness.On the diameters, the ethmoid cells were slender and columnar, and the radial walls of the ethmoid cells were arranged in a single line.The ray cells in the phloem were larger than those in the xylem.The number of axial parenchyma cells in the old secondary phloem increased and the number of ray cells decreased.The pericarp is composed of cork cells, which are filled with dark matter and arranged in imbricate shape.The special leaf structure of Ningxia includes epidermis, mesophyll and vascular tissue.The leaf is spirally placed on the axis and on the cross-section. The leaf is semicircular, trapezoid, or triangular.A layer of epidermal cells arranged closely, the epidermis covered with a developed cuticle, in which there are cylindrical or striped protrusions.Mesophyll cells differentiate into palisade tissue and sponge tissue.There were obvious stomatal bands on the leaf epidermis, which were arranged in parallel and longitudinally, and the stomatal apparatus was surrounded by a pair of renal guard cells and peripheral accessory cells.The endodermis consists of a layer of parenchyma, which is surrounded by vascular tissue, including vascular bundles and transfer cells.Leaves with a vascular bundle, not branched; transferred cell polygon, cell wall with holes.The resin channel is missing.
【学位授予单位】：云南大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：Q914.3

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