Electronic Flora of South Australia Genus Fact Sheet

Genus SEIROCOCCUS Greville 1830: xxxiv

Phylum Phaeophyta – Order Fucales – Family Seirococcaceae

Thallus 0.5–2 m long, much branched laterally and essentially complanately, with long axes or primary branches, slightly flexuous and bearing marginally alternate, distichous, simple, laterals 4–12 mm broad; vesicles absent; stipe single, with a discoid and marginally hapteroid holdfast. Growth from 1–3 four-sided apical cells in an apical depression. Structure with a medulla of elongate cells with hyphae, and a cortex of isodiametric cells with a surface meristoderm.

Reproduction: Thalli monoecious. Receptacles densely clustered along the adaxial axillary margins of laterals and spreading to the margin of the parent branch, terete, verrucose, 2–5 (–8) mm long and 0.5–1 mm in diameter. Conceptacles usually bisexual; oogonia sessile, with an apical mesochiton collar and a single egg; antheridia on branched paraphyses.

Type and only species: S. axillaris (Turner) Greville.

Taxonomic notes: Seirococcus is closely related to Scytothalia in habit and dimensions, but differs in having short, terete receptacles in contrast to the flat, ensiform to lanceolate and often rostellate ones of Scytothalia.

Seirococcus occurs on eastern coasts of southern Australia, but overlaps with the distribution of the western Scytothalia.


GREVILLE, R.K. (1830). Algae Britannicae. (Edinburgh.)

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
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