Clubmosses exist in two different forms, although only the aboveground spore producing variety is commonly seen. The leaves of these plants are long and narrow like needles, and strobili, cone-like clusters of diminutive leaves, are usually present as well. At the base of each clubmoss strobilus is a small yellowish-orange sporangium, where the reproductive spores are produced and stored. When conditions are right, the sporangium bursts, releasing the spores, many of which rapidly grow into bisexual gametophytes. In some species, however, the development into the gametophytic form of the plant may take substantially longer, requiring as many as eight years to complete.