虎耳草科虎耳草属石荷叶组叶下表皮斑点的形态学研究

Morphological Studies of Leaf Abaxial Epidermic Spots in section Irregulares(Saxifraga,Saxifragaceae)

东亚地区广泛分布的虎耳草科(Saxifragaceae)虎耳草属(Saxifraga L.)的基部类群石荷叶组(section Irregulares Haw.)物种在园艺、中草药和植物分类研究中具有重要的价值,但在应用和研究中常常出现物种混淆、界定不清等问题。叶片下表皮是否具有斑点是石荷叶组传统形态分类中一个重要的定种特征,常用于分辨蒙自虎耳草(S.mengtzeana),但在传统中草药虎耳草(S.stolonifera)的叶下面也常出现与蒙自虎耳草及其近缘种类似的浅绿色至紫红色斑点。为了解这些物种的斑点是否具有相同的形态与解剖结构,本研究对石荷叶组和部分虎耳草属物种进行了叶片形态学观察,主要结果包括:具有叶下表皮斑点的物种,其斑点所在表皮具有聚集的气孔,而没有斑点的物种,气孔在下表皮均匀分布;斑点下存在一个较大的气穴和散生晶体;斑点颜色各异,存在个体差异;斑点大小和密度在虎耳草种间乃至虎耳草的新、老叶中均具有显著差异;试验观察的石荷叶组虎耳草气孔类型为平列型。研究结果可以对虎耳草属园艺植物和中药材的鉴定、石荷叶组物种的分类提供一定的理论依据与指导。

Section Irregulares Haw.,the basal group of Saxifraga L.(Saxifragaceae),is widespread in East Asia and of great value in horticulture,herbal application and plant classification.But miss identification and obscure definition often occur in its applications and researches.One of the crucial defining characters is the existence of leaf abaxial epidermic spots,often used to identify S.mengtzeana.However,S.stolonifera,a Chinese traditional herbal medicine,also has similar pale green or purple spots on its leaf abaxial surface,like S.mengtzeana and its relatives.To understand whether the spots in these species have the same morphological and anatomical structures,this study conduct some leaf morphological observations for some sect.Irregulares and genus Saxifraga species,and the main results are as follows:stomata cluster on spots in those species with leaf abaxial epidermic spots,while those without leafy spots,the stomata evenly distribute on the abaxial surface;underneath the spot is a large air space and scattered crystals;the spots are different in color and sometimes the differences lay in individual level;there are significant differences in spot size and density between Saxifraga species,new and old leaves of S.stolonifera;the sect.Irregulares species observed have paracytic stomata.The results could provide some theoretical supports and directions to the identifications of Saxifraga horticultural plants,herbal medicine,and the classification of sect.Irregulares.