Abstract: The amounts and relative contents of n-alkanes in epicutiuclar wax of seven species of Polygonaceae were analyzed using GC technology, and the crystal morphology of epicuticular wax was observed by SEM. The experiment aims to provide a new path for plant chemical classification and scientific theory for utilizing and developing Polygonaceae. Results showed that the amounts and relative contents of n-alkanes in the epicuticular waxes were different among species. The relative content of odd-numbered n-alkanes was significantly higher than that of even-numbered n-alkanes. The most abundant n-alkanes were C₂₉, C₃₁ and C_33, and the relative contents of n-alkanes < C₂₇ and >C₃₃ were relatively lower. The carbon preference index (CPIs) of long chain n-alkanes ranged from 1.1 to 7.1, while the CPIs of short chain n-alkanes ranged from 0.6 to 3.1. SEM analysis showed that a dense, diffused wax film was covered on leaf surface of tested plants and crystals were spread over the film. The predominant wax crystal type of Polygonum posumbu, P. capitatum, Rumex patientia and P.chinense was granular, that of Fallopia multiflorum was long rod, and that of P. hydropiper and Fagopyrum dibotrys was flat. Seven species of four genera in Polygonaceae could be clustered into two groups. One was P. posumbu mainly containing C₁₉ and C₂₁, the others included plants mainly containing C₂₉, C₃₁ or C₃₃.

Key words: Polygonaceae, Epicuticular wax, Relative contents of n-alkanes, Wax crystal morphology

摘要： 采用气相色谱技术测定了蓼科（Polygonaceae）4属7种植物叶表皮蜡质正烷烃的含量和相对含量，并通过扫描电镜（SEM）观察了叶表皮的蜡质晶体形态，旨在为植物化学分类提供新的途径，同时也为合理开发利用蓼科植物资源提供科学依据。结果表明：蓼科植物叶表皮蜡质中正烷烃的含量和相对含量均存在种间差异，且奇数烷烃的相对含量明显高于偶数烷烃，其中C₂₉和C₃₁的相对含量最高，其次是C₃₃，碳链27和 >C₃₃的烷烃的相对含量较低。长链烷烃的碳优势指数（CPIs）在1.1~7.1之间，短链烷烃CPIs在0.6~3.1之间。植物叶表均覆盖一层蜡质薄膜，弥漫性分布于叶表。蜡质薄膜之上散布蜡质晶体，其中丛枝蓼（Polygonum posumbu）、头花蓼（P. capitatum）、巴天酸模（Rumex patientia）和火炭母（P. chinense）的蜡质晶体主要呈颗粒状，何首乌（Fallopia multiflorum）呈杆状，水蓼（P. hydropiper）和金荞麦（Fagopyrum dibotrys）呈片状。蓼科4属7种植物经聚类后可分为2大类：Ⅰ类仅包括以C₁₉和C₂₁为主要烷烃的丛枝蓼，Ⅱ类包括以C₂₉，C₃₁或C₃₃为主要烷烃的其他6种植物。

关键词: 蓼科, 表皮蜡质, 正烷烃相对含量, 蜡质晶体形态