小花山桃草营养器官解剖结构及其生态适应性研究

通过石蜡切片法对外来入侵植物小花山桃草进行解剖学方面的研究，旨在揭示其入侵和蔓延的结构基础。结果表明：小花山桃草根的次生结构中次生木质部所占比例较大，约占整个横切面的2/3，导管数量多，平均达138.25个，管腔大，管径为85.37 μm；根和茎的木栓层均较发达，由6～7层扁平细胞组成；根和茎的次生韧皮部中存在大量含针晶细胞；小花山桃草的叶具典型的旱生植物叶片的结构特征：表皮为复表皮，上下表皮均有气孔分布，上表皮气孔密度为180 mm^-2,下表皮气孔密度为266 mm^-2；栅栏组织为双栅型，近轴面栅栏组织细胞2～3层，排列紧密而整齐，含叶绿体较多；叶片主脉木质部发达，由多列导管组成。上述特征说明小花山桃草的解剖结构对干旱生境有较强的适应性。

Anatomical Structures of Vegetative Organs and Ecological Adaptation of Gaura parviflora

Gaura parviflora is one of the invasive plants, the anatomical structure of its vegetative organs was studied by the methods of paraffin section. The results showed that: In the secondary structure of the roots of G. parviflora，there was a larger proportion of secondary xylem, about two thirds of the entire cross section, the number of vessels averaged 138.25, and the lumen diameter was 85.37 μm; The cork of the roots and stems were both developed, which was composed of 6 to 7 layers of flat cells; there were many parachyma cells containing needle crystals in the secondary phloem; The leaves of G.parviflora had the typical characteristics of xerophytes leaves: the multiple epidermis; the stomata existed in both upper and lower epidermis，whose densities were 180 mm^-2 and 266 mm^-2, respectively; the palisade tissue was two-side palisade which included 2 to 3 layers of cylindrical cells in the upper side, with a lot of chloroplasts; the main vein of leaves had well developed xylem ,with a number of radial arranged vessels. The characters mentioned above showed that G.parviflora adapted well to the dry environment.