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Electronic Flora of South Australia Genus Fact Sheet

Genus HYMENENA Greville 1830: xlviii

Phylum Rhodophyta – Family Delesseriaceae

Thallus foliose to much branched, essentially complanate, erect and becoming stipitate or prostrate; holdfast rhizoidal or fibrous. Midribs absent or present, microscopical veins present. Structure. Growth marginal, without distinct apical cells. Young blades monostromatic, becoming tristromatic and polystromatic in central or older regions; cortical cells equivalent to primary cells, in anticlinal tiers where polystromatic. Stipes developed from thickened midribs, bare or with proliferations. Microscopic veins slender or coarse, 1–4 cells broad.

Reproduction: Gametophytes dioecious. Procarps scattered, with the supporting (cortical) cells producing 2 sterile cells and a 4-celled carpogonial branch, surrounded by pericarp initials. Carposporophytes with a basal fusion cell and much branched gonimoblast with terminal carposporangia, replaced from below in some species. Cystocarps swollen on both surfaces usually with a short neck; pericarp ostiolate, thick, with anticlinal rows of cells. Spermatangial sori on branch ends, with a layer of initials producing groups of elongate spermatangia.

Tetrasporangial sori on branches, usually ovate, with inner cortical cells producing 2 layers of tetrasporangia laterally, covered by outer cover cells; tetrasporangia tetrahedrally divided.

Type species: H. fissa Greville 1830: xlviii = H. venosa (Linnaeus) Krauss 1846: 209.

Taxonomic notes: A genus of some 20 species, with 3 species (including several synonyms) on southern Australian coasts. The type species was investigated by Wagner (1954, p. 321, figs 176–188, 191, 193–199).

Hymenena is characterised by the presence of microscopic veins and by single terminal carposporangia. These veins are slender and 1 cell broad in most species, but in H. curdieana are relatively coarse and 2–4 cells broad.


GREVILLE, R.K. (1830). Algae Britannicae. (Maclachlan & Stewart: Edinburgh.)

KRAUSS, F. (1846). Pflanzen des Cap- und Natal-Landes, gesammelt und zusammengestellt von Dr Ferdinand Krauss. Flora 29, 209–219.

WAGNER, F.S. (1954). Contributions to the morphology of the Delesseriaceae. Univ. Calif Pubis Bot. 27, 279–346.

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

Author: H. B. S. Womersley

Publication: 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.


1. Thallus usually 8–20 (–25) cm high, erect and complanately branched, mid and lower branches usually 4–10 mm broad


1. Thallus usually 5–10 cm high, densely tufted, branches 1–2 (–3) mm broad


2. Lower axis usually well developed, covered with small proliferous bladelets; microscopic nerves coarse, usually 2–4 cells broad

H. curdieana

2. Lower axis weakly developed, without proliferous bladelets; microscopic veins slender, one cell broad

H. affinis

3. Branches more-or-less complanate, midrib slight

H. multipartita

3. Upper branches convolute, developing midribs shortly below the apices

H. endiviaefolia

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