Like other plants, most mosses reproduce through the alternation of generations, alternating generations of sexual and asexual forms; each complete life cycle requiring two generations. The sexual form, called the gametophyte, begins as a protonema. The protonema is the direct product of spore germination and gives rise to the green leafy plant commonly regarded as a moss. The asexual form, or sporophyte, develops as separate male and female plants, but neither can exist independently. Each sporophyte plant is composed of a capsule, which is the center of spore formation; a stalk; and a foot that attaches the sporophyte body to the tip of the gametophyte. Eventually, the diploid spores are released and, upon successful germination, grow into another moss plant.