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Genus PLACOPHORA J. Agardh 1863: 1137

Phylum Rhodophyta – Family Rhodomelaceae – Tribe Placophora

Thallus prostrate, flat, foliose, simple or branched, a few mm broad, and mostly 2 cells thick, epiphytic on Codium and other algae. Structure. Marginal apical cells terminating branched axial filaments, the axial cells cutting off 3 dorsal and 2 ventral pericentral cells (hence primarily dorsiventral), with the filaments laterally fused to give the flat thallus; trichoblasts absent from prostrate axes. Branching of the main axial filaments in alternate pairs of cells, of the lateral axes one to several cells apart. Rhizoids cut off from ventral pericentral cells.

Reproduction: Reproductive organs formed on short, free, polysiphonous branches on thallus margin; gametophytes dioecious. Procarps on the basal cell of short trichoblasts, with a 4-celled carpogonial branch and 2 sterile cells; carposporophyte with clavate terminal carposporangia; cystocarps ovoid, pericarp ostiolate, 2 cells thick, ecorticate. Spermatangial organs on branches of trichoblasts, elongate, with 3–4 sterile apical cells.

Stichidia with 5–7 pericentral cells, with tetrasporangia single per segment, lying in a longitudinal series, each with 2 cover cells.

Type species: P. binderi (J. Agardh) J. Agardh 1863: 1138.

Taxonomic notes: A genus of 2 species originally described from South Africa, the type now known to be relatively widespread in the southern hemisphere, and P. eckloniae Pocock only known from South Africa. Adams (1994, p. 333, pl. 115 lower right) describes an un-named species from New Zealand, needing verification as a Placophora.

The most detailed description of Placophora binderi and P. eckloniae is by Scaegel (1953).


ADAMS, N.M. (1994). Seaweeds of New Zealand. (Cant. Univ. Press: Christchurch.)

AGARDH, J.G. (1863). Species Genera et Ordines Algarum. Vol. 2, Part 3, pp. 787–1291. (Gleerup: Lund.)

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

Publication: Womersley, H.B.S. (24 February, 2003)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIID. Ceramiales – Delesseriaceae, Sarcomeniaceae, Rhodomelaceae
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIID 2003, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.

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