杜鹃花属植物花粉形态及其分类学意义

利用扫描电子显微镜对5个亚属20种杜鹃花属植物的花粉形态进行了观察和比较研究,其中大部分(16种)为首次报道。杜鹃花属花粉均为四合花粉,呈正四面体排列。四合体为圆角三角形,连接紧密。单粒花粉为球形或近球形,具三沟孔。在扫描电镜下,除了杜鹃亚属的百合杜鹃、羊踯躅亚属的羊踯躅以及马银花亚属的马银花组具有明显的纹饰特征之外,其它类群的形态特征相互重叠,不足以作为现有亚属的分类依据。花粉粒具不同的外壁纹饰,可为分类研究提供孢粉学方面的证据,但应慎重应用花粉形态对杜鹃花属植物特定种进行分类鉴定。

Pollen morphology of Rhododendron and its taxonomic implication

Pollen grains of 20 species of 5 subgenera in the genus Rhododendron L.were observed by scanning electron microscope(SEM). Most of them(16 species)were examined for the first time. All of them are arranged in tetrahedral tetrad and the shape of tetrad is orbicular triangle and adjoin tightly. Pollen grain of Rhododendron are spheroidal or subspheroidal with tricolporate. Among the different subgenus,only three taxa,subgen.Rhododendron(e.g.,R.liliflorum),subgen.Azaleastrum(e.g.,R.ovatum,R.mitriforme,R.bachii)and subgen.Pentanthera(e.g.,R.molle),can easily be distinguished from the rest taxa,in which pollen morphological characteristics are overlapped each other. The difference of pollen exine sculpture between sections in the genus can provide palynology proof for further taxonomy. However,the identification of some certain species in Rhododendron by morphological data of pollen should be analyzed carefully.