Androecium contains stamens. Each stamen which represents the male reproductive organ which has of a stalk or a filament and an anther. Each anther is bilobed and each lobe has two chambers, the pollen-sacs. The pollen grains are produced in pollen-sacs. A sterile stamen is called staminode. Stamens of flower are united with other members such as petals or among themselves. When stamens are attached to the petals, they are epipetalous as in brinjal, and when attached to the perianth they are epiphyllous as in the flowers of lily. The stamens in a flower are either free (polyandrous) or united in varying degrees. The stamens may be united into one bunch or one bundle (monoadelphous) as in china rose, or two bundles (diadelphous) as in pea, or into more than two bundles (polyadelphous) as in citrus. There may be a variation in the length of filaments within a flower, as in Salvia and mustard.