Nereocystis luetkeana

Scientific classification

(unranked):     SAR

Superphylum: Heterokonta

Class:   Phaeophyceae

Order: Laminariales

Family:            Laminariaceae

Genus: Nereocystis

Species:           N. luetkeana

Binomial name           Nereocystis luetkeana

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 Pacific Coast of North America, from Southern California to the Aleutian Islands, Alaska.

The thallus of this common canopy-forming kelp has a richly branched holdfast (haptera) and a cylindrical stipe 10–36 m (33–118 ft) long, terminating in a single, gas-filled pneumatocyst from which the many blades, up to 10 m (33 ft) long, develop.

Blade growth can reach 15 cm (6 in) per day. Reproductive patches (sori) develop on the blades and drop to the seafloor at maturity.

This annual kelp grows on rock from the low intertidal to subtidal zones; it prefers semi-exposed habitats or high-current areas. Offshore beds can persist for one to many years, usually in deeper water than Eualaria or Macrocystis, where they co-occur.

The species Nereocystis luetkeana was named after Fyodor Petrovich Litke (also spelled Lütke) by Mertens (first as Fucus luetkeanus) and then described by Postels and Ruprecht.