Abstract: Pollen morphology of five species from China in the genus Gymnadenia R. Br. (Orchidaceae) was investigated in this work. Pollen characteristics of this genus were compared to those of its closely related genus, Neottianthe Schltr. It is found that there are some differences of pollen morphology between the two genera, e.g.: (A) Pollen massulae are mostly irregular less frequently trigonous-conical in Gymnadenia, while mainly trigenuus-conical less frequently irregular in Neottianthe; (B) Ornamentation of pollen exine surface is usually indistinct, but microperforate, microrugulate, microfoveolate or both microperforate and microfossulate in high magnification in Gymnadenia, but more distinct in Neottianthe. Exine ornamentation of this genus can be divided into five types, ( 1 ) almost smooth, or very obscurely fosset, (2) perforate, (3) fossulate or foveolate, (4) reticuloid, (5) typically reticulate. (C) the surface of pollen massulae in Gymnadenia possess viscin thread, but that in Neottianthe does not. The result of this work supports the separation ofNeottianthe from Gymnadenia as an independent genus.

Key words: Pollen morphology, Gymnadenia R．Br．