荆条叶片解剖结构及其生态适应性研究

Anatomical Structure of Vitex negundo L.var.heterophylla (Franch.) Rehd. Leaves and Its Ecology Adaptation

通过石蜡切片，利用光学显微镜对荆条[Vitex negundo L.var.heterophylla（Franch.） Rehd.]叶片结构进行观察。结果表明，荆条叶片具有旱生植物典型的形态特征，为典型异面叶，由表皮、叶肉和叶脉三部分组成。上、下表皮细胞均为单层，排列整齐而紧密。上表皮的外切向壁有角质层和少量表皮毛（腺毛和非腺毛），而下表皮具有大量表皮毛，多为非腺毛。具有孔下室。叶肉发达，内富含叶绿体，分化明显，栅栏组织2～3层，多为3层，海绵组织排列疏松，细胞间隙大，形状不规则。叶脉主脉中木质部发达，侧脉中维管束结构逐渐简化。以上特征与干旱贫瘠的环境条件相适应。

The paraffin slices of Vitex negundo L.var.heterophylla （Franch.） Rehd. leaves were observed under light microscope.The results showed that the leaves of Vitex negundo L.var.heterophylla （Franch.） Rehd. had typical morphological characteristics of xerophytes. It had typical bifacial leaf composed of epidermis,mesophyll and vein. The cells of both upper and lower epidermis were monolayer and arranged closely and tightly. The outside cell wall of upper epidermis had cuticle and a little trichome （glandular and nonglandular）. The lower epidermis had much more trichomes and most of them were unglandular.There were lots of chambers under stomata in lower epidermis. The mesophyll was strong and riched in chloroplast. The mesophyll tissue differentiated obviously with 2-3 layers of palisade tissue,more than the 3 layers,and irregular-shaped spongy tissue arranged loosely with large gap among cells. The xylem in the midrib of vein was strong,while the vascular bundle in the lateral vein simplified gradually. The characteristics mentioned above were suitable for drought circumstances.