An antheridium is a haploid structure or organ producing and containing male gametes (called antherozoids or sperm). The plural form is antheridia, and a structure containing one or more antheridia is called an androecium. Androecium is also the collective term for the stamens of flowering plants. The female counterpart to the antheridium in cryptogams is the archegonium, and in flowering plants is the gynoecium.