Nereocystis (Greek for "mermaid's bladder") is a monotypic genus of kelp containing the species Nereocystis luetkeana. Some common names include edible kelp, bull kelp, bullwhip kelp, ribbon kelp, giant kelp, bladder wrack, and variations on these names. It forms thick beds on rocks, and is an important part of kelp forests. It can grow to a maximum of 36 m (118 ft).Nereocystis has a holdfast of about 40 cm (16 in), and a single stipe, topped with a pneumatocyst containing carbon monoxide, from which sprout the numerous (about 30-64) blades. The blades may be up to 4 m (13 ft) long, and up to 15 cm (5.9 in) wide. It is usually annual, sometimes persisting up to 18 months. Nereocystis is the only kelp which will drop spore patches, so that the right concentration of spores lands near the parent's holdfast. It is common along the coast of the northeastern Pacific Ocean, from about Monterey, California to Aleutian Islands, Alaska.