Earlier this spring I collected some samples of algae for my botany class to observe and managed a small sample of Chara, also known as muskgrass, to put in the lab. It has been growing well with frequent water changes and has developed lots of the reproductive structures called gametangia (structures that produce gametes, or sperm and eggs). The type of gametangia that produce sperm are called antheridia and are seen as the bright orange structures in image below.
And here is a closeup of an antheridium
Somewhat less abundant are the oogonia, where eggs are produced and where fertilization takes place. The oogonia on this particular specimen have an interesting twist to them, although I do not know if this is typical of all Chara spp. or just this one.
