常绿杜鹃亚属麻花杜鹃亚组11种3变种植物叶片微形态特征及其分类学意义

Leaf Micromorphological Characteristics and Taxonomic Significance of 11 Species,3 Varieties in Subsect.Maculifera,Subgen.Hymenanthes(Ericaceae)

杜鹃花属种类繁多,广泛分布于欧亚大陆和北美大陆,由于种间变异大、过渡特征丰富,其分类鉴定一直存在较多争议。该研究通过扫描电镜对常绿杜鹃亚属(subgen.Hymenanthes)麻花杜鹃亚组(subsect.Maculifera)的11种3变种植物的叶表皮微形态特征进行观察,为麻花亚组的分类与鉴定提供新的依据。结果显示:麻花杜鹃亚组植物上表皮表面平滑或粗糙、无表皮毛,具有条状、分枝状或短杆状初级蜡质纹饰;下表皮表面有或无分枝状蜡质纹饰,少部分具有表皮毛,不具有指状或乳状突起、亦无腺体;气孔器形状为圆形或椭圆形,内外拱盖表面粗糙或光滑,周围无间断的条形突起环绕。研究表明,麻花杜鹃亚组植物叶片微形态特征表现出一定的共性与多样性,可为麻花杜鹃亚组植物的分类和进化研究补充形态学依据。依据本研究观察结果对麻花杜鹃亚组进行了分类检索,并讨论了叶表皮微形态特征在该亚组近缘物种和种下类群研究中的分类学意义。

Rhododendron L.is a large genus of Ericaceae and widely distributed in Eurasia and North America.The infrageneric classification of Rhododendronis acontroversial issue due to a large number of variations andtransitional characters.Micromorphological characters of leaf epidermis from 11 species and 3varieties of subsect.Maculifera,subgen.Hymenanthes were examined using scanning electron microscope（SEM）.The result shows the following characters：the adaxial lepidermis surface is smooth or rough,no foliar trichomes,ornamentations include strips,branching and short rod shapes;the abaxial epidemis surface has branching waxy ornamentation or not,some have foliar trichomes,without fingers of protuberance or eglandular.The stomatal apparatus are round or oval,with rough or smooth inside and outside the stoma,but without interrupted strip or other abnormal ornamentation around.The above micromorphological characters show certain similarities and differentia,which could provide new evidence for classification and evolution researches.Based on micromorphological characters of leaf epidermis,keys are generated,andthen the taxonomic use of these characters in affinitive species and infraspecies are also discussed.