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Order Ceramiales

Family Rhodomelaceae

Placophora J. Agardh

Vegetative thallus prostrate, foliaceaous, formed by lateral fusion of polysiphonous axes. Erect cylindrical polysiphonous branches often forming on thallus surface, some of these becoming reproductive. Segments with five pericentral cells, two ventral, one dorsal. Every segment in principle producing a branch, branches arranged in pairs on alternating sides. Thallus attached by rhizoids cut off from ventral pericentral cells. Reproductive structure developing on erect, free, radially symmetrical branches produced either from margins of prostrate axes or adventitiously from dorsal pericentral cells on thallus margins. Fertile filaments cylindrical or slightly compressed, with ca 7-10 pericentral cells. Tetrasporangia one per segment in dorsal straight series, with two cover cells. Spermatangia in conical heads that develop from trichoblasts on some subapical segments. Cystocarps spheroidal to urceolate, usually one per free branchlet. Three species are currently recognized, two of which occur in South Africa.

Key to species

1a. Free polysiphonous filaments rarely more than 0.5 mm long

P. binderi

1b. Free polysiphonous filaments up to 5 (-10)mm or more

P. monocarpa

 

 

Cite this record as:

Anderson RJ, Stegenga H, Bolton JJ. 2016. Seaweeds of the South African South Coast.
World Wide Web electronic publication, University of Cape Town, http://southafrseaweeds.uct.ac.za; Accessed on 18 September 2018.