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Electronic Flora of South Australia Genus Fact Sheet

Genus LOMENTARIA Lyngbye 1819: 101

Phylum Rhodophyta – Class Florideophyceae – Order Rhodymeniales – Family Lomentariaceae

Thallus erect or forming entangled clumps, much branched, with or without percurrent axes, branches terete or compressed, hollow, basally constricted with solid septa; holdfast discoid or hapteroid. Structure multiaxial, with a cluster of apical cells developing an inner cortex 2–3 cells thick and an outer cortex of small cells sometimes forming rosettes, and a medulla of a network of interconnected filaments bearing secretory cells; basal branch septa pseudoparenchymatous.

Reproduction: Gametangial thalli dioecious. Carpogonial branches 3-celled, borne on inner cortical (supporting) cells together with a 2-celled auxiliary cell branch. Carposporophyte with a relatively massive, erect, fusion cell producing slender gonimoblast filaments and clusters of cells, all becoming carposporangia; basal nutritive tissue present, erect filaments disintegrating. Cystocarps external, globular to urceolate, pericarp 3–6 cells thick, ostiolate. Spermatangia cut off via initials on outer cortical cells.

Tetrasporangia in depressed sori, cut off thallus inwardly from small cells lining the depression, tetrahedrally divided.

Life history triphasic with isomorphic gametophytes and tetrasporophytes.

Holotype species: L. articulata (Hudson) Lyngbye 1819: 101.

Taxonomic notes: A genus of about 40 species, with three species known from southern Australia, characterised by thallus structure, external cystocarps and depressed tetrasporangial son.


LYNGBYE, H.CH. (1819). Tentamen Hydrophytologiae Danicae. (Copenhagen.)

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (28 June, 1996)
The Marine Benthic Flora of Southern Australia
Rhodophyta. Part IIIB. Gracilarialse, Rhodymeniales, Corallinales and Bonnemaisoniales
Reproduced with permission from The Marine Benthic Flora of Southern Australia Part IIIB 1996, by H.B.S. Womersley. Australian Biological Resources Study, Canberra. Copyright Commonwealth of Australia.


1. Branching irregularly radial, branches terete except for larger ones which may be slightly compressed; inner cortical cells mostly L/B 1.5–2.5, with outer cells forming distinct rosettes

L. australis

1. Erect branches compressed, simple or pinnate and largely distichous, inner cortical cells of younger branches more or less isodiametric, outer cells few, scarcely forming rosettes


2. Erect fronds pinnate, 2–20 (–45) cm high, axes (2–) 3–4 (–5) mm broad

L. pyramidalis

2. Erect fronds simple, 0.5–2 mm broad, arising from entangled stolons in clumps 2–5 cm high

L. monochlamydea

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