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Electronic Flora of South Australia Family Fact Sheet
Phylum Rhodophyta
Thallus multicellular, filamentous with filaments discrete or compacted to a pseudoparenchyma, of various forms, a few calcified (especially Corallinales). Structure uniaxial or multiaxial, cell divisions apical or rarely intercalary, cells uninucleate or multinucleate with a central vacuole, rhodoplasts usually parietal, laminate, stellate, ribbon shaped or discoid, in primitive families often with a pyrenoid. Pit-connections present.
Reproduction: In some taxa by monospores or other asexual spores. Sexual reproduction oogamous and normally present, involving carpogonia with elongate trichogynes, usually terminal on a several-celled branch, and in most orders auxiliary cells which are formed before or after fertilization and diploidized via direct fusion with, or by connecting filaments from, the fertilized carpogonium. Carposporophyte formed by the fertilized carpogonium or the diploidized auxiliary cell, usually producing gonimoblast filaments bearing terminal chains or clusters of carposporangia; the carposporophyte may lie within the thallus or external to it, and may be surrounded by a cellular envelope or pericarp. Spermatangia are cut off from initials derived from surface cells, occasionally in pits, with non-motile spermatia.
Tetrasporophytes with cruciately, tetrahedrally or zonately divided tetrasporangia.
Life history usually triphasic with (usually) macroscopic gametophytes and tetrasporophytes and minute carposporophytes; in some taxa monophasic or biphasic.
Taxonomic notes: The class Florideophyceae is distinguished by the presence of pit-connections, apical growth of filaments, and by the complex sexual reproduction involving carpogonial branches and the presence in most orders of generative auxiliary cells from which the carposporophyte develops; meiotic tetrasporangia usually occur in a separate generation, the tetrasporophyte.
References:
CRONQUIST, A. (1960). The divisions and classes of plants. Bot. Rev. 26, 425–482.
The Marine Benthic Flora of Southern Australia Part IIIA complete list of references.
Publication:
Womersley, H.B.S. (14 January, 1994)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIA, Bangiophyceae and Florideophyceae (to Gigartinales)
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIA 1994, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.
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