中国钩藤属9种植物的花粉形态

Pollen Morphology of Nine Chinese Species of Uncaria Schreb. (Rubiaceae)

利用光学显微镜和扫描电镜对中国钩藤属(Uncaria Schreb.)9种植物的花粉形态进行了观察。结果表明,钩藤属植物的花粉为单粒,小型,辐射对称,赤道面观圆球形至近长球形,极面观3-裂圆形,具3孔沟,萌发沟裂缝状,长达两极。萌发沟中央有"内壁加厚突出"结构。外壁具条纹至细网纹饰,表面光滑无附属物。钩藤属花粉大小、形状、萌发沟和纹饰类型都较接近,属于单一型花粉。钩藤属植物的花粉形态特征是茜草科(Rubiaceae)中较为原始的类型。

Pollen morphology of nine Chinese species of Uncaria Schreb. was observed using scanning electron microscopy （SEM） and light microscopy （LM）. The pollen grains are monad, small, radically symmetrical, and tricolporate, with a spheroidal to subprolate shape in equatorial view and three-lobed circular shape in the polar view. The ectocolpus is crack-like up to poles. A protruding oncus is often found in the middle of the ectocolpus. The exine ornamentation is striate to microreticulate, and without supratectal element. The genus Uncaria is fairly stenopalynous, because of a lack of variation of pollen characteristics at species level. The pollen morphology of Uncaria belongs to plesiomorphic type in Rubiaceae.