Pollen morphology of Pedicularis sect. Cyathophora, a group endemic to the Eastern Himalaya-Hengduan Mountains region.

Pedicularis sect. Cyathophora is a distinctive group endemic to the eastern Himalaya-Hengduan Mountains region. It was regarded as a 'grex' or section and included all four general corolla types of Pedicularis. A unique feature of it is that the leaf and bract bases are fused together to form a cup-like structure around the stem at each node. Pollen morphology of seven species in sect. Cyathophora was investigated by scanning electron microscopy (SEM) and light microscopy (LM). Two different pollen apertures could be distinguished (i.e. trisyncolpate and bisyncolpate) using LM, while examination with SEM made it possible to recognize three types of exine ornamentation (i.e. microscabrate, microfoveolate and microreticulate). The microfoveolate exine ornamentation was found in trisyncolpate pollen grains for the first time. Possible relationships between pollen data and the corolla types were discussed. Comparisons of floral and phyllotaxy characters of the genus Pedicularis, together with the pollen characters of sect. Cyathophora, could help us to better understand the evolutionary trends in Pedicularis.