Climbing hydrangea pollen. Coloured scanning electron micrograph (SEM) of pollen grains of Hydrangea petiolaris. Hydrangea petiolaris, a climbing hydrangea is a species of flowering plant in the family Hydrangeaceae native to the woodlands of Japan, the Korean peninsula, and on Sakhalin island of easternmost Siberia. Hydrangea petiolaris is cultivated as an ornamental plant in Europe and North America. Pollen grains are the male sex cells of a flowering plant. Their characteristic surface is used by botanists to recognise and classify plants. Pollen in plants is used for transferring male genetic material from the anther of a single flower to the stigma of another in cross-pollination. In a case of self-pollination, this process takes place from the anther of a flower to the stigma of the same flower. Magnification: x250 when printed at 10cm wide.