A branch of Cystocera geminata shown by Joe Downham –photos by Ryan Murphy

C.geminata sub-tidally at Race Rocks

Cystoseira geminata
Description: This plant is profusely branched, yellowish brown to dark brown in colour, reaching a height of 2-5 m. The plant is fastened to the substrate by a stout discoid holdfast.           A short, terete stipe arises from the holdfast. This stipe is soon dissected into a number of stout radially arranged primary branches, which in turn bear long filiform secondary branches.         The long filiform branches produce shorter alternately arranged tertiary branchlets. Near the base these tertiary branchlets undergo a few divisions, become markedly flattened and leaf-like, and give the basal region of the plant the appearance of a fern frond. These flattened branches are short, lanceolate in shape, with smooth margins, and are ribless.           The ultimate branchlets have inflations, or air vesicles, borne singly or in pairs or chains.

Habitat:           On rocks in the lower intertidal and upper subtidal zones.

Pacific Coast Distribution:           Bering Sea to Washington.
Robert Scagel, 1972

Scientific classification
Kingdom: Chromalveolata
Phylum: Heterokontophyta
Class: Phaeophyceae
Order: Fucales
Family: Fucaceae
Genus: Cystoseira geminata (L.) C.Agardh, 1820 [1]

Return to the Race Rocks Taxonomy and Image File

The Race Rocks taxonomy is a collaborative venture originally started with the Biology and Environmental Systems students of Lester Pearson College UWC. It now also has contributions added by Faculty, Staff, Volunteers and Observers on the remote control webcams. Ryan Murphy, PC Year 26