【作者】 闫桂华；

【导师】 王立军；

【作者基本信息】 吉林农业大学 ， 植物学， 2011， 硕士

【摘要】 梓树(Catalpa ovata)为紫葳科(Bignoniaceae)梓树属(Catalpa scop)植物,又称河楸、黄花楸等,多年生木本。在我国分布很广,为中国的乡土树种,世界各国大都进行引种。梓树较喜光,适宜温暖气候,但其耐寒力极强,能耐-45℃的极端低温,亦耐干旱贫瘠土壤,能耐轻盐碱土,其抗污染性较强。有关梓树的繁殖栽培、园林绿化及药用价值方面已经做了初步的研究,并取得了很大的成果。梓树作为优质的的园林绿化树种具有较高的生态意义和经济意义,具有较高的开发利用前景。本文采用石蜡切片、木材制片等方法,对梓树(Catalpa ovata)幼苗初生维管系统、营养器官及内部结构同抗旱性、抗寒性的关系与系统演化进行了研究和分析。结果表明：1.梓树幼苗的初生维管系统幼苗的子叶节区较长,自上到下都有髓的存在,为向基移位型(Basipetal shifting type)。子叶节区下部具有中始式四原型管状中柱,在子叶节区中部的原生木质部处一分为二,逐渐形成具有8枚外韧维管束的中柱结构；在子叶节区上部,组成短轴的2枚维管束各自一分为三,逐渐形成真中柱的雏形,与上胚轴的分生组织性组织分化形成的内始式真中柱相连接,至此,子叶节区发育完成。子叶为单隙三迹。2.梓树次生根的结构根系发达,为深根性。次生根的导管孔多为近圆形,口径较大,数量多,且多数组成复管孔或管孔团,导管靠近髓射线分布。轴向薄壁组织发达,为傍管型,带状。髓射线发达,多由3-4列射线细胞组成,射线细胞的体积较小。这说明梓树根系具有较强的输导水分及抗旱能力。3.梓树的茎材结构在横切面上：树皮具有内皮和外皮之分,韧皮细胞含有较多的内含物,韧皮纤维发达,并同韧皮薄壁细胞间隔排列。韧射线发达,多由2列细胞组成。木材为环孔材,生长轮明显；早材管孔近圆形,多为单管孔,管孔团较少见,壁较厚：在心材的导管内有侵填体的存在；晚材管孔为圆形或多边形,多组成复管孔、管孔团或管孔链,导管壁较薄；轴向薄壁组织发达,为傍管型。在径切面上：木射线由方形细胞、横卧细胞、直立细胞组成,属异型木射线。细胞端壁上具明显的节状加厚,水平壁纹孔十分明显。在弦切面上：木射线排列密集,异胞,非叠生,单列或者多列,多为异形Ⅱ。解离细胞特征：在解离的细胞中,纤维的数目多,且长度相差较大；导管较长,按有无尾端及尾端的长短可分为四种类型。4.梓树叶的内部结构特征叶的上、下表皮均具有较厚的角质层、腺毛及较长的多细胞表皮毛,这些表皮附属物是梓树防止水分流失及增强抗寒性的结构特征。气孔数目多,体积小,仅分部在叶的下表皮。在横切面上可以看出,梓树的叶片较厚,叶肉细胞发达,具有栅栏组织和海绵组织之分；栅栏组织排列紧密,细胞较小,一般2-3层,且长、宽比例大；海绵组织排列疏松,并有游离细胞的存在,栅栏组织/海绵组织的比值大于1。叶片的主脉较突出,且主脉表皮细胞明显比叶片上、下表皮细胞体积小,排列紧密,其上分布有较多的表皮毛。主脉维管束较发达,在近轴面的叶脉中出现了三束异常的维管束；在远轴面的维管束呈环状排列,与幼茎的维管束像似。在主脉表皮上未见有气孔的存在。同时,在梓树叶的表皮上分布有较多的蜜腺,蜜腺较小,且结构简单,一般仅有单一的基细胞和一列纵行排列的分泌细胞组成,不具有专门的维管组织。按腺细胞相对于表皮细胞的位置,可以分为突出型和凹进型两种。更多还原

【Abstract】 Catalpa ovata is a perennial deciduous shrub of Catalpa Scop in Bignoniaceae. It is widely distributed over our country and is native tree specie in china. It grows in sun and is suitable to warm climate but has great cold resistance, arid soil, light saline-alkali soil and pollution of environment. The primary studies on its culture and breeding, landscaping and medicinal value have made great achievements. As high grade seeds of tree, Catalpa ovata is of great ecological and economic value, having widely potential application.The primary vascular system of seedling and anatomical structure were studied through paraffin section method and wood section method, as well micro-technology. The results were as follows:1. The primary vascular system of seedling of Catalpa ovataThe cotyledon node zone (CNZ) of Catalpa ovata is longer, and belongs to basipetal shifting type. From top to bottom, it has pith in the whole CNZ. There is mesarch tetrarch siphonostele in the lower portion of the CNZ, which divides into two parts from protoxylem in the middle portion of the CNZ and gradually form stele structure with eight collateral bundles. In the upper portion of the CNZ, two vascular bundles which formed shorter axis divide into three parts respectively and shape the model of eustele, then connect with endarch eustele of epicotyl. There is three-trace cotyledonary node in the seedling.2. The structure of Catalpa ovata secondary rootThe root system is well-developed, and belongs to rooting plant. The vessels of secondary which hole is mostly round, bigger pipe diameter are a lot, mostly formed pore multiple or pore cluster, and near to pith ray. Axial parenchyma is well-developed, banding, and belongs to paratracheal parenchyma. The pith ray is well-developed formed from two or three rows pith cells, and the pith cell is small. All of the structure features illustrate that Catalpa ovata root system has strong translocation and drought resistance.3. The structure of Catalpa ovata timberIn the transaction, the bark can be divided into hardback and soft back. Phloem parenchyma has much tannin, and phloem fiber is well-developed which alternates with phloem cells. The phloem fiber is also well-developed, mostly with two rows of cells. The timber belongs to rind pored wood, and its growth ring is evident; The hole of vessel of spring wood get on for roundness, solitary, few of pore cluster, thin-wall, and having thylose in duramen; The hole of vessel of summer wood is roundness or polygon, mostly formed pore multiple or pore cluster, thick-wall. Axial parenchyma is well-developed, and belongs to paratracheal parenchyma.In radial longitudinal section, xylem ray includes cubiodal cell, procumbent cell, upright cell, which belongs to heterogeneous ray. The cell wall has section shape thickening.In tangential section, xylem ray arranges tightly, not storied ray, uniseriate or multiseriate ray, and most belong to heterogeneous II ray, few belong to heterogeneous I ray.The characteristics of dissociation:the amount of fiber takes up to overwhelming majority, and the fiber length is different very much.; The vessels is longer which can classify five types, in terms of tail end or the length of tail.4. The structure of Catalpa ovata leafThe upper and lower epidermis have think horny layers, wax layers, glandular hairs, and long multicellular epidermis hairs which all named dermal appendages can help Catalpa ovata prevent water loss and enhance cold resistance. There are a lot of stomas in the lower epidermis. In the transaction, there are thick upper epidermis, thick developed lamina which can be divided into palisade tissue and spongy tissue; The palisade tissue is compactness, including two or three layers, and its cells are small, which length is bigger than width; The spongy tissue arranges loosely and has free cells, and the proportion of thickness between palisade tissue and spongy tissue is bigger than one.Main vein of Catalpa ovata leaf is more prominent. The epidermis cells of main vein which arrange more closely than the epidermis cells of leaf are smaller and have more multicellular epidermis fairs. The vascular bundles in main vein are well-developed, and there are three abnormal vascular bundles in abaxial surface; the vascular bundles arrange a circle in adaxial surface which is similar to younger stem. There isn’t stoma in the epidermis of main vein.At the same time, there are many small nectarines in epidermis of leaves, and the structure of nectary is simple which just has a basal cell and bristling secretory cells, without special vascular tissue. The gland cells can classify bulge and recessed types, in terms of the positions which are relative to epidermis cells.更多还原