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Electronic Flora of South Australia Genus Fact Sheet

Genus CAULOCYSTIS Areschoug 1854: 334

Phylum Phaeophyta – Order Fucales – Family Cystoseiraceae

Thallus usually 10–60 cm long, with a short stipe from a discoid-conical holdfast, bearing 1–4 primary branches with later juvenile branches from the stipe. Primary branches straight, terete, bearing dense, radially arranged, laterals of limited growth, usually denuded below with short scars remaining. Laterals simple or (usually) laterally branched one to several times, terete, with occasional lower laterals developing further. Vesicles borne on the primary branches or occasionally on lower parts of older laterals which develop further, pedicellate, subspherical to ovoid or fusiform. Growth from a three-sided apical cell. Structure of a central medulla of elongate cells, cortex of isodiametric cells, and surface phaeoplastic meristoderm developing a thick cortex on lower branches; cryptostomata prominent.

Reproduction: Receptacles developed from ends of ramuli, pedicellate, swollen, terete and smooth, usually 1–3 cm long, with bisexual conceptacles with scattered ostioles; basal columella with phaeophycean hairs present. Oogonia with a single egg.

Lectotype species: C. uvifera (C. Agardh) Areschoug.

Taxonomic notes: A genus of two species, endemic to southern Australia, characterised by the straight, terete, radially branched primary branches with vesicles borne directly on the primary branches. Most specimens are separated on vesicle shape, but intermediates are often numerous; it is possible that the two species recognised here are ecological forms, but genetic differences are probably also present.


ARESCHOUG, J.E. (1854). Phyceae novae et minus cognitae in maribus extraeuropaeis collectae. Ada Reg. Soc. Sci. Upsala, Ser. III, 1, 329–372.

The Marine Benthic Flora of Southern Australia Part II complete list of references.

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (14 December, 1987)
The Marine Benthic Flora of Southern Australia
Part II
©Board of the Botanic Gardens and State Herbarium, Government of South Australia


1. Vesicles subspherical to slightly ovoid when adult, 3–9 mm in diameter

C. uvifera

1. Vesicles elongate-ovoid, tapering at both ends, 3–10 mm long and 2–5 mm broad

C. cephalornithos

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