Pollen morphology ofPinus(Pinaceae) in northeast China

The pollen morphology of eight taxa representing Pinus species of Pinaceae in northeast China was examined by light microscopy and scanning electron microscopy. The pollen grains were bisaccate monads. A single elongate outlined (monosulcate) aperture was observed on the distal pole between the sacci (air sacs) and the sculpture pattern of the corpus (pollen body) was verrucate or rugulate, while sacci were foveolate on either smooth or coarse surfaces. A key to pollen types of Pinus in northeast China was developed based on whether the sacci outline in polar view was discontinuous (diploxylonoid) or continuous (haploxylonoid) with the corpus outline, and on the exine sculpture patterns on the corpi and sacci. The pollen types were Densiflora, Koraiensis, Sylvestris, and Tabulaeformis. The pollen width with sacci was highly correlated with the corpus width.