Cystoseira is characterized by highly differentiated basal and apical regions and the presence of catenate pneumatocysts (air-vesicles). In Cystoseira old plants have an elongated main axis, and in time the primary laterals become proportionally elongated. Their lower parts are strongly flattened into ‘foliar expansions’ or basal leaves. Fertile regions which bear conceptacles are known as receptacles. These are normally found at the tips of the branches. Their basal and apical regions are highly differentiated. They have catenate pnuematocysts (air vesicles). The aerocyst or air vesicles keep the organism erect, by causing it to float in strong currents.

Original publication: Kützing, F.T. (1860). Tabulae phycologicae; oder, Abbildungen der Tange. Vol. 10 pp. i-iv, 1-39, 100 pls. Nordhausen: Gedruckt auf kosten des Verfassers.
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Pardi, G., Piazzi, L. & Cinelli, F. (2000). Demographic study of a Cystoseira humilis Kützing (Fucales: Cystoseiraceae) population in the western Mediterranean. Botanica Marina 43: 81-86, 6 figs.

Serio, D., Alongi, G., Catra, M., Cormaci, M. & Furnari, G. (2006). Changes in the benthic algal flora of Linosa Island (Straits of Sicily, Mediterranean Sea). Botanica Marina 49: 135-144.

Engelen, A.H., Espirito-Santo, C., Simões, T., Monteiro, C., Serrão E.A., Pearson, G.A. & Santos, R.O. P. (2008). Periodicity of propagule expulsion and settlement in the competing native and invasive brown seaweeds, Cystoseira humilis and Sargassum muticum (Phaeophyta). European Journal of Phycology 43(3): 275-282.

Type information
Type locality: “Tanger” (Kützing 1860: 18). Type: L? Notes: Athanasiadis (1996: 219) lists Kap Spartel, Morocco as the type locality.