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Phaeophyta, Brown Algae

Cystoseira spinosa Sauvageau

Phaeophyta,  Order: Fucales; Family: Cystoseiraceae.


The scientific name, Cystoseira, means chain of vesicles, and it describes the air pockets in the thallus. The scientific name of the species describes the pedicles found upon the toful and along the entire plant.


The Cystoseira spinosa has a single compact, unbranched holdfast. It has a short stipe split into several branches. The base of the stipe contains a thorny toful (condensation), hence the species’ name. The branches are also covered in pedicels. The sporangia are concentrated at the base of the stipe or within the branches, location varying among the different sub-species.


Most individuals found were 10-30 cm in length, but some are larger.


The species is characterized by shades of light brown and cream, sometimes uniformly, and sometimes spots can be seen. Upon drying, the thallus becomes darker.

Special features

The Cystoseira spinosa’s most characteristic feature is its profusion of pedicles.

The Cystoseira spinosa appears in the intertidal zone, in pools and potholes, usually up to a depth of 10 m.

Biology and reproduction

The conceptacales and the cryptoblasts of the Cystoseira spinosa appear all over the thallus, on the stipe and within the axis, amongst its ‘leaves’ or on the ‘branches’.

Seasonality and distribution

The Cystoseira spinosa is very common throughout the Mediterranean, and probably also in the Eastern Mediterranean. The species is perennial.

Additional species

The Cystoseira spinosa has several sub-species differentiated by the location of their sporangium - at the base of the ‘leaves’ or along the ‘stalk’. The Cystoseira spinosa Sauvageau var. tenuior (Ercegovi.) Coemaci, et al.: this sub-species was identified in Israel. It is probably the most common variant in the Eastern Mediterranean, and appears in the upper levels, at depths of less than 10 m. In the past, it has been erroneously called Cystoseira adriatica Sauvageau. Cystoseira spinosa Sauvageau var. spinosa is a var. of Cystoseira spinosa characterized by the fact that some of its branches are flattened. Cystoseira spinosa Sauvageau var. compressa (Ercegovi.) Coemaci, et al. also has flattened branches and was formerly referred to as Cystoseira platyramosa Ercegovi.

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