Abstract: Leaf epidermal morphology of 26 species ( including 1 subspecies and 2 varieties) of Lasianthus and 6 species of its related 4 genera Morinda , Psychotria , Saprosma and Urophyllum, were investigated under both light microscope (LM) and scanning electron microscope (SEM) . It was shown that the shapes of upper leaf epidermal cells varies from irregularly sinuolate, nearly elliptic to irregularly polygonal. The lower leaf epidermal cells are usually irregularly sinuous or sinuate. The patterns of anticlinal walls are sinuate irregularly , and the ambits are inconspicuous between the cells. It was found that the cell walls of both upper and lower epidermis are covered with thick corticle . Under SEM, the cuticula membrane of the leaf epidermis is distinct, and granular, reticulate, scaly or papilliform in shape. The stomatal apparatus is of paracytic type and occurs only on the lower surface. The stomatas of some species are sunken. Leaf indumentum of Lasianthus species can be classified into single-celled hairs and uniseriate multi- celled hairs including linear, twisted and straight-walled hairs. The leaf epidermal morphology of the related genera in Rubiaceae is similar to Lasianthus. In conclusion, the leaf micro-morphological characteristics have some significance in identification of Lasianthus species, but show regular varia-tion with habitats. The variations of the ratio between stomatal polar axis and outer stomatal ledge aperture, as well as leaf indumentum of Lasianthus species are well correspondent to their habitats .

Key words: Leaf epidermal

摘要： 利用光学显微镜和电子扫描显微镜研究了亚洲茜草科粗叶木属植物26 种( 包括1 个亚种和2 个变种) 和相关4 属即巴戟天属、九节属、染木属和尖叶木属6 种植物的叶表皮微形态特征。粗叶木属植物上表皮细胞形状一般呈不规则波状、近椭圆形或者不规则多边形, 下表皮细胞一般呈不规则皱波状或者多裂深波状, 细胞壁曲折无章, 细胞间界限不明显, 上、下表皮细胞壁均有加厚现象。叶表皮角质层明显, 在电镜下有以下几种类型: 颗粒状, 网状, 鳞片状, 乳突状。气孔器几乎全部生在下表皮, 有些种气孔下陷, 气孔器一般是一对保卫细胞和一对副卫细胞平列。一些粗叶木属植物种叶上着生表皮毛。表皮毛分为单细胞毛和单列多细胞毛两种结构类型以及扭曲毛, 线形毛和直壁毛3 种形态类型。相关属的叶表皮微形态特征与粗叶木属植物较为相似。粗叶木属植物叶表皮微形态特征具有一定的分类学价值, 其性状虽有遗传稳定性, 但随生态环境不同而有一定变异。粗叶木属植物叶气孔长轴径􊄯径轴变化幅度比较大以及叶表
皮上的毛被多样化均能反映其对生态环境的适应变化。

关键词: 叶表皮, 微形态, 粗叶木属