Electronic Flora of South Australia Genus Fact Sheet
Phylum Rhodophyta – Family Rhodomelaceae – Tribe Herposiphonieae
Thallus basally attached but with free upper parts, axes branched, bearing simple or branched, alternate, distichous, determinate laterals separated by a single unbranched segment. Attachment by clumped rhizoids. Structure. Pericentral cells 8, 2 larger on each face and 2 slightly smaller on each margin, the latter sometimes dividing transversely; corticating cells occur in irregular clusters on each side of the axes, lying over the ends of pericentral cells and on the margins. Trichoblasts apparently absent. Rhizoids cut off from adjacent pericentral cells and hence clumped, individually unicellular with multicellular haptera.
Reproduction: Carposporophytes with a basal fusion cell and branched gonimoblast with clavate terminal carposporangia. Cystocarps ovoid; pericarp ostiolate, ecorticate. Spermatangial organs unknown.
Tetrasporangia in determinate laterals, spirally arranged, one per segment.
Type species: G. maugeana Womersley, sp. nov.
Taxonomic notes: Gredgaria is characterised by the pattern of branching, pericentral cells and corticating cell clusters, and clumped rhizoids. It is named after Dr Graham Edgar, whose extensive collections off Tasmania coasts (in particular) have contributed to our knowledge of the algae of this region.
References: The Marine Benthic Flora of Southern Australia Part IIID
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.
State Herbarium of South Australia