Flower of Geranium "Rozanne", a hybrid garden plant ( G. himalayense x G wallichianum "Buxton's variety" ). The picture shows the centre of a recently opened flower. A ring of ten stamens in visible, bearing anthers (dark purple) that have opened to revealnumerous pollen grains (small yellow spheres). The red masses amidst the anthers are as yet undeveloped stigmas, the receptive female tissue to which the pollen grains attach themselves. In common with many Geranium species, the female tissues develop and mature after the male anthers have shed their pollen. This is called protandry, and in nature promotes cross-pollination. "Rozanne" is a sterile hybrid; it does not produce seed. As a result it has a long flowering period, and was voted Plant of The Centenary by the Royal Horticultural Society in 2013.