Pollen is the male gametophyte of seed plants. Both gymnosperms (cone-bearing plants) and angiosperms (flowering plants) produce pollen as part of sexual reproduction. In gymnosperms pollen is produced in microsporangiate cones (male cones or pollen cones), while in angiosperms pollen is produced in the anthers (part of the stamen within the flower). Each pollen grain typically consists of one to a few cells. The wall of the pollen grain consists of two layers, the exine (outer wall) and intine (inner wall). The exine may be smooth or ornamented with spines, warts, granules, pores or furrows.