They are also known as brittleworts or skunkweed, from the fragility of their lime-encrusted stems, and from the foul odor these produce when stepped on.

They are unique in having a whorl of small branchlets at each node in the stipe which gives them a superficial resemblance to the genus Equisetum.

[citation needed] There are about 400 extant species worldwide, with 33 in Britain and Ireland according to Groves and Bullock-Webster),[2][3] however Stewart and Church (1992) reduce this to 21.

[4] Characeae are the principal photosynthesizers of some of the volcanic crater lakes of Nicaragua, and can be found in excess of 20 meters depth in some circumstances.

[9] They are usually found in low to medium nutrient-rich water and tend to disappear due to eutrophication.