Plant is erect,cylindrical (or slightly tapering), flattened or strap shaped, simple or branched, may be several metres high, annual or perennial, usually epilithic (grows on other plants). Sap of the annual species contains sulfuric acid, pH may be as low as 1. Plants left on rocks in the sun can etch their shape onto the rocks, when collected must be kept separated from other seaweeds or they will destroy them.

Widely distributed in polar to warm-temperate seas. Dominant and stand-forming in Antarctica and some parts of the Arctic.

Uses sun's energy for photosynthesis.

Can be used to make sour pickles.

http://www.algaebase.org/search/genus/detail/?genus_id=56&-session=abv4:8B502C6B1d6be38A5COhvTF07C1A (accessed 06/12/10)