Electronic Flora of South Australia
Electronic Flora of South Australia
Census of SA Plants, Algae & Fungi
Identification tools

Electronic Flora of South Australia Family Fact Sheet


Phylum Rhodophyta – Class Florideophyceae – Order Gigartinales

Thallus erect, foliose to much branched, soft and mucilaginous to firm and cartilaginous, with or without a distinct stipe. Structure multiaxial with a medulla of slender to robust, sparse to dense, filaments and a cortex of ovoid cells in anticlinal filaments or pseudoparenchymatous, medulla with or without stellate or refractive ganglioid cells (which have darkly staining and refractive contents). Rhodoplasts discoid to elongate, few to many per cortical cell.

Reproduction: Sexual thalli monoecious or dioecious, non-procarpic. Carpogonial branches 2-celled, on a primary ampulla filament (in the inner cortex) which develops secondary filaments which surround the carpogonial branch, or in Zymurgia 4-celled without an ampulla; connecting filaments developing from the fertilized carpogonium. Auxiliary cell ampullae arising in the inner cortex, with the auxiliary cell within or on a primary filament which develops secondary filaments and in some genera up to five orders of filaments, with the auxiliary cell lying at or near the base of the ampulla with the filaments either converging above or remaining cupulate (in the outer cortex). Carposporophyte developed from the diploidized auxiliary cell towards the thallus surface, with most cells becoming carposporangia usually within gonimolobes, surrounded by a slight to conspicuous involucre derived from the ampullary filaments or also including medullary filaments; ostiole present or not. Spermatangia cut off from surface cortical cells.

Tetrasporangia scattered in the outer cortex, sometimes in sori, or between paraphyses in slightly raised nemathecia, cruciately divided.

Life history triphasic with isomorphic gametophytes and tetrasporophytes.

Taxonomic notes: A family of about 20 genera, well represented on southern Australian coasts with some 11 genera. The family is clearly characterised by its thallus structure and sexual reproduction, involving carpogonial branches and auxiliary cells borne in filamentous ampullae. However, separation of many of the genera requires further study and, hopefully, recognition of better features for their separation. The family is clearly in need of further study and generic placement of several species described below is tentative.

This family has been known as the Cryptonemiaceae Harvey (1849b, p. 132) and the Grateloupiaceae Schmitz in Engler (1892, p. 18), but Guiry (1978, p. 192) has pointed out that Halymeniaceae Bory 1828 is the earliest valid name.


BORY DE ST-VINCENT, J.B. (1828). In Duperrey, L.I., Voyage autour du monde, exécuté par ordre du Roi, sur la corvette de Sa Majesté, la Coquille, pendant les années 1822, 1823, 1824 et 1825. Botanique, Cryptogamie, pp. 1–300, Plates 1–39. (Bertrand: Paris.)

ENGLER, A. (1892). Syllabus der Vorlesungen über specielle and medicinisch-pharmaceutische Botanik ... Grosse Ausgabe. (Borntraeger: Berlin.)

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

HARVEY, W.H. (1849b). A manual of the British marine algae. Edn 2. (Van Voorst: London.)

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. Surface of thallus smooth, without minute excrescences; reproductive organs borne in the normal thallus


1. Surface of thallus rough and covered with minute excrescences or of fibrils forming a meshwork often with associated sponge; reproductive organs borne in small (less than 1 cm long) flat leaflets on the upper thallus, free from sponge


2. Thallus subdichotomous or laterally branched, branches 0.1–2 (–40) cm broad, firm, drying cartilaginous (not mucilaginous), with or without a perennial thickened stipe or prominent midrib; not or partly adhering to paper on drying


2. Thallus much branched with narrow branches or broad and foliose, soft to firm, surface mucilaginous, without a perennial thickened stipe or prominent midrib, usually not cartilaginous and adhering to paper on drying


3. Thallus subdichotomously to irregularly branched or foliose, branches usually more than 4 mm broad; tetrasporangia scattered in the cortex


3. Thallus repeatedly subdichotomously to alternately branched, branches usually 1–6 mm broad, ovate in section or strongly compressed; tetrasporangia in sori or in slightly raised nemathecia on upper branches


4. Thallus complanately branched, branches 1–6 (–8) mm broad, often with a slight lower midrib; medulla less than one third of the thallus in thickness; outer cortex pseudoparenchymatous, with or without distinct anticlinal filaments of elongate cells; one species with a thick cover of sponge


4. Thallus slightly compressed, 1–2.5 mm broad, subdichotomous or proliferous; medulla more than half the thallus in thickness, outer cortex of anticlinal filaments of elongate cells; sponge absent


5. Medulla in young and mid thallus lax, with sparse filaments, becoming denser in older parts; auxiliary cell ampullae relatively simple in most taxa, with few secondary or tertiary filaments (or more elaborate in some species of Grateloupia); ampullary involucre slight to prominent


5. Medulla throughout of moderately to densely entwined filaments; auxiliary cell ampullae much branched and bushy; ampullary involucre prominent


6. Thallus slender, densely radially branched, branches terete. Carpogonial branches 4-celled, borne on inner cortical cells, without ampullae; auxiliary cell ampullae with few branches, cupulate


6. Thallus slender to robust, usually largely complanately branched Carpogonial branches 2-celled, within an ampulla; auxiliary cell ampullae cupulate or converging; involucre present


7. Medulla in young parts with sparse filaments mostly transverse, becoming dense with irregular filaments in older parts; refractive ganglionic cells usually present; auxiliary cell ampullae broad, not converging above; thallus foliose or complanate and pinnate


7. Medulla of sparse, loosely entwined filaments; refractive ganglionic cells absent; auxiliary cell ampullae with few or many branches, usually converging above; involucre slight to prominent; thallus usually much branched, in some species slightly branched and proliferous or foliose


8. Thallus complanately branched, pinnate to bipinnate, with prominent axes 1–2 cm broad and tapering laterals


8. Thallus foliose to irregularly lobed, 5–30 cm across


9. Cortex of anticlinal filaments of 4–10 elongate cells, branched every 2–5 cells; medulla dense, filaments of two thicknesses; auxiliary cell ampullae with short basal cells and numerous branches of small ovoid cells; involucre dense, becoming compact; holdfast basal, stipe prominent


9. Cortex of anticlinal filaments of 2–4 ovoid to elongate cells, branched every 1–2 cells; medulla moderately dense, filaments of uniform thickness, auxiliary cell ampullae with ovoid cells, much branched, involucre thick, of short cells; holdfast submarginal, stipe very slight


10. Thallus branches 1–4 (–10) mm broad, bearing short, irregular, surface excrescences; medulla dense, cortex densely pseudoparenchymatous


10. Thallus branches 4–8 (–11) cm broad, formed of intermeshing filiform laterals; holdfast and lower stalks massive


Disclaimer Copyright Disclaimer Copyright Email Contact:
State Herbarium of South Australia
Government of South Australia Government of South Australia Government of South Australia Department for Environment and Water