西藏色季拉山区龙胆科植物种子微形态特征及其系统分类学意义

Micromorphological characteristics of Gentianaceae seeds in Shergyla Mountain area of Tibet and their systematic and taxonomic significance

利用扫描电镜和解剖镜对西藏色季拉山区分布的龙胆科6属20种植物种子微形态进行观察研究。结果显示:这20种植物的种子颜色有黑色、黄色、黑褐色、黄褐色、灰褐色和红棕色6种;种子形状分为长卵球形、卵球形、椭圆球形、矩圆形和近球形;表皮纹饰可分为4种类型,即网纹型、条纹型、疣状型和嚼烂型,其中网纹型又细分为6个亚型。根据种子微形态特征,笔者对龙胆科相关属的进化趋势、分类学意义和分类鉴定等进行了讨论,认为獐牙菜属(Swertia L.)和龙胆属(Gentiana(Tourn.)L.)进化程度较高;从种子微形态特征上看肋柱花属(Lomatogonium A.Br.)、花锚属(Halenia Borkh.)和假龙胆属(Gentianella Moench.)间有较近的亲缘关系;龙胆科各属种子表皮纹饰特征与分类系统基本吻合。本研究表明种子微形态在植物分类研究中具有十分重要的意义,可作为植物系统划分、鉴定和进化研究的参考性状。

Scanning electron microscopy and stereoscope were used to observe the seed micromorphology of 20 species from six genera of the Gentianaceae family in the Shergyla Mountain area of Tibet.Results showed that the seeds of these 20 plants were black,yellow,dark brown,tan,taupe,and reddish brown and seed shape was divided into long ovoid,ovoid,elliptical,oblong,and nearly spherical.Skin ornamentation could be divided into mesh,striped,scorpion,and chew types,with the textured type further subdivided into six subtypes.According to the micromorphological characteristics of seeds,we investigated the evolutionary trends,taxonomic significance,and classification identification of genus Gentianaceae,and found that Swertia L.and Gentiana(Tourn.)L.showed a relatively high degree of evolution.Based on the micromorphological characteristics of the seeds,we identified a close relationship among Lomatogonium A.Br.,Halenia Borkh.,and Gentianella Moench.The characteristics of seed skin ornamentation of the genus Gentianaceae were relatively consistent with the classification system.This study shows that seed micromorphology is of significance in plant taxonomic studies and can be used as a reference trait for the study of plant system division,identification,and evolution.