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Electronic Flora of South Australia Family Fact Sheet


Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales

Thallus usually erect, flat and furcately or laterally and usually complanately branched, or terete. Structure uniaxi al, axial filament conspicuous or not, cortex pseudoparenchymatous, inner cells multinucleate with secondary pit-connections, medulla filamentous or pseudoparenchymatous; surface view usually showing rosettes of small cells around larger inner cells.

Reproduction: Sexual thalli dioecious; procarpic and monocarpogonial. Carpogonial branches 3 (–4)-celled, usually laterally directed (with an outwardly directed trichogyne) on the supporting cell (an inner or mid cortical cell),with a cell pit-connected above the supporting cell serving as the auxiliary cell; gonimoblast initial single, developing thallusinwardly or laterally, with adjacent cortical cells producing branches of small nutritive cells. Carposporophytes with either a large fusion cell or several central cells, with radiating gonimoblast filaments terminating in chains of carposporangia; sterile filaments between the gonimoblast and surrounding cortical cells may occur, but filamentous enveloping tissue is usually absent; cystocarps immersed or protruding, often with a cortical pericarp, usually non-ostiolate. Spermatangia scattered over outer cortical cells of young parts of branches.

Tetrasporangia scattered in outer cortex, terminal or intercalary, zonately divided.

This family was monographed (Australian taxa) by Min-Thein & Womersley (1976) under the name Rhodophyllidaceae Schmitz (1892, p. 19). Since then Guiry (1978, p. 193) has pointed out that Cystocloniaceae Kützing (1843, p. 390) is an earlier name.

The family includes some 10 genera, 7 of which occur on southern Australian coasts.

Life history triphasic with isomorphic gametophytes and tetrasporophytes.


GUIRY, M.D. (1978). Notes on some family names of Florideophyceae (Rhodophyta). Taxon 27, 191–195.

KÜTZING, F.T. (1843). Phycologia generalis. (Leipzig.)

MIN-THEIN, U. & WOMERSLEY, H.B.S. (1976). Studies on southern Australian taxa of Solieriaceae, Rhabdoniaceae and Rhodophyllidaceae (Rhodophyta). Aust. J. Bot. 24, 1–166.

SCHMITZ, F. (1892). Florideae. In Engler, A., Syllabus der Vorlesungen Ober spezielle und medicinisch-pharmaceutische Botanik. Eine Ubersicht fiber das gesammte Pflanzensystem mit Berticksichtigung der Medicinal-und Nutzpflanzen. Grosse Ausgabe. (Berlin.)

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

Author: H.B.S. Womersley

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.


1. Thallus compressed to flat or foliose, at least in older axes, usually complanately and marginally branched; medulla narrow, filamentous or of large cells


1. Thallus terete, linear or segmented, irregularly or subverticillately branched; medulla broadly filamentous or of large cells


2. Thallus not complanately branched, terete above, older branch axes becoming compressed, to 5 mm broad; axial cells elongate-ovoid, without rhizoidal filaments


2. Thallus distinctly flattened throughout, older parts over 5 mm broad, complanately branched; axial cells elongate-linear, often with rhizoidal filaments around the axial cells or as a thin medulla


3. Thallus usually less than 1 cm broad, at least in upper parts, irregularly branched and often with marginal proliferations; surface rosettes present, slightly to well developed; medulla filamentous but usually slight, in some species consisting only of elongate axial filaments


3. Thallus commonly over 1 cm broad in lower and upper parts, subdichotomously or irregularly branched, without proliferations (marginal spines in Stictosporum); surface rosettes obscure or absent; a filamentous medulla present, with large ovoid cells on either side; axial cells not apparent


4. Thallus usually with weakly developed rosettes; vein system weakly developed; cystocarps with a distinct, central, fusion cell


4. Thallus with well developed rosettes; vein system often clearly developed; cystocarps with a central group of larger cells which do not fuse


5. Thallus irregularly branched, without regular marginal spines, proliferations absent or occasional; gonimoblast developing inwardly


5. Thallus subdichotomous, with a fringe of marginal spines 0.5–1 mm long; gonimoblast developing outwardly


6. Thallus of elongate-ovoid segments; branching subverticillate, medulla broad, filamentous with a central axial filament; cystocarps developed in the medulla


6. Thallus terete, linear; branching irregular, medulla cellular


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