Cycas revoluta, a cycad from Japan. Cycads are very primitive plants and fossil representatives of the family date back some 300 million years. This photograph shows a new whorl of leaves appearing in early spring; cycads are very slow-growing and this is not an annual occurrence. They are dioecious, the male flowers produce large quantities of pollen which germinates to form motile spermatozoids. There are about 100 species, some of which, the sago palms, are used as a source of food because of the starchy nature of the stem and seeds.