14种石斛属(兰科)植物的花粉团形态及分类学意义

利用体式显微镜和扫描电镜观察了14种石斛的花粉团形态及其表面纹饰超微特征,为该属的物种划分和系统演化提供花粉形态证据。解剖镜下,14种石斛的花药里有4枚花粉团,表面金黄油亮呈蜡质,质地坚硬。根据每种石斛的4枚花粉团的总体轮廓形态和大小,可分为3种形态(心形、近心形和长心形)和4种类型(极小花粉团,小花粉团,大花粉团和超大花粉团)。根据单个花粉团边界轮廓的曲直,可将其分为4种类型(月牙型、弓型、棍状和米粒型)。扫描电镜下,14种石斛的花粉团表面纹饰类型有5种(光滑平整型、光滑带丝状突起型、光滑不平整型、粗网纹状型和皱波状型),在广东石斛和球花石斛的花粉团表面观察到晶体的存在。花粉团的形态大小和外壁纹饰特征在种间变化明显,对澄清石斛属的分类学问题有一定意义。

Pollinia Morphology of 14 Species in Dendrobium(Orchidaceae)and Taxonomic Significance

The morphology and exine sculpture of pollinia in 14 species ofDendrobium Sw.(Orchidaceae)were investigated using stereoscope and scanning electron microscope in order to provide evidence for classification and systematic evolution of this genus.Under stereomicroscope,the anther is composed of 4 clavated pollinia with a golden,oily,waxy surface and a hard texture in 14 Dendrobium species.According to the general appearance,Dendrobium pollinia observed can be divided into 3 shapes(heart-shaped,nearly heart-shaped and long heart-shaped)and 4 types(extremely small pollinia,small pollinia,large pollinia and oversize pollinia).Based on the curvature of the boundary contour of a pollinium,it can be divided into four types(crescent-like,bow-like,stick-like and rice grain-like).There are 5 kinds of exine sculptures(psilate;psilate with threads;psilate-uneven,coarse reticulate and rugulate)under scanning electron microscope,as well as two types of crystals observed on the surface of pollinia in D.wislsonii Rolfe and D.thyrsiflorum Rchb.The morphology and exine sculpture of pollinia were distinguished in different species of Dendrobium,which is of some significance to its taxonomic clarification.