Polygamous, in botany, signifies "having flowers both perfect and imperfect (i.e. bisexual and unisexual) on the same plant," as in the ash, the maples, horse-chestnuts, and most Composite (q.v.). The horse-chestnut illustrates a common principle, the lower or first-formed flowers being bisexual, or having both stamens and carpels; while the upper, later-formed ones are male, i.e. staminate. In the Compositaa various arrangements occur, the most frequent being that in the daisy, where the centre or disk florets in each head are bisexual, and the outer or ray florets are female, i.e. pistillate.