Study On The Morphological Structure And Developmental Anatomy Of Catalpa Ovata

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.