Antheridium of Bracken
An illustration of the anteridium of a bracken. An antheridium (plural: antheridia) is a haploid structure or organ producing and containing male gametes (called antherozoids or sperm). Brackens (Pteridium) are a genus of about ten species of large, coarse ferns, in the family Dennstaedtiaceae. The genus has probably the widest distribution of any fern genus in the world, being found on all continents except Antarctica and in all environments except for hot and cold deserts. Therefore it is considered to have a cosmopolitan distribution.