Sand pines (Pinus clausa) are monooecious: Male and female flowers are on the same plant. Flowers begin to form in early summer but do not become visible until autumn.
Male flowers – staminate stobili — of the sand pines at south Oslo Riverfront Conservation Area are getting ready to release their pollen (pictured above & below). Female flowers — pistillate strobli — develop into pine cones. Conelet development is minimal during the first year and increases rapidly during the second year. Sand pines can begin to bear cones at five years of age.