Leptosiphonia brodiei is a dark purplish red alga which grows 30 to 360 mm tall in erect or prostrate tufts. The thalli can be attached by rhizoids from a prostrate axis. or by a clump of rhizoids 1-3 mm in diameter, supporting an erect axis. Branches are alternate, with naked straight tips There may be up to 5 orders of branching, creating a bushy appearance. Leptosiphonia brodiei occurs from the low-intertidal. down to 20 m depth. It was described from Bantry Bay, Ireland, and occurs from Norway to the Mediterranean, the Black Sea, Madeira, the Canary and Cape Verde Islands, and the Azores. Populations in the Gulf of St. Lawrence, and the Bay of Fundy were introduced before 1971, probably by ballast water of hull fouling. Other introduced populations are reported from Australia, New Zealand and Atlantic South America. Other populations, in the Indian Ocean, Japan. California. and Alaska are considered cryptogenic The Polysiphonia species group is taxonomically difficult, and being revised through molecular analysis.