Pollen Morphology of Vaccinium ashei J.M.Reade.(Ericaceae),with Reference to a Measurement Method of Polar Coordinate for Tetrahedral Tetrads

Pollen morphology of Vaccinium ashei was investigated by scanning electron microscopy.Most of pollen grains are tetrahedron with tetrad construction.Most of the apertures were tri-zonocol porate,distributed symmetrically at the three sides by the axis of symmetry of the tetrahedron.The pollen grains with different ecological styles of germinal apertures in length,width,length and width of lid,shape of lid and the extent of protuberances etc.,especially with several hollows could be the factors resulting in the different germination of pollen grains.The shapes and forms of tetrahedral tetrads grains may be described with a new method of polar coordinate that is more exact and more direct than with traditional measurement method of polar axis(P) and equatorial axis(E).