Electronic Flora of South Australia Species Fact Sheet

Rhizoclonium tortuosum (Dillwyn) Kützing.

Phylum Chlorophyta – Order Cladophorales – Family Cladophoraceae

Selected citations: Chapman 1939: 20. Setchell & Gardner 1920b: 185.


Conferva tortuosa Dillwyn 1805, pl. 46. Harvey 1846: pl. 54A.

R. riparium f. validum Foslie. Koster 1955: 351.

Thallus light to medium green, forming mats of entangled filaments in shaded, upper eulittoral, calm-water habitats. Filaments (Fig. 53C) unbranched, in some cases without but in other material with lateral, 1–5 celled, rhizoids (Fig. 53B). Cells (23–) 25–40 (–45) nm in diameter, L/B (1.5–) 2–3 (–4), wall 3–5 (–8) nm thick; chloroplast moderately to densely reticulate with numerous pyrenoids.

Reproduction: Reproduction unknown for Australian (or European?) plants.

Type from Yarmouth, England; in BM (see Chapman 1939, p. 21).

Distribution map based
on current data relating to
specimens held in the
State Herbarium of SA

Distribution: Europe, Britain, N. America, New Zealand; probably widely distributed.

In southern Australia, known from Picnic Point, American R. inlet, Kangaroo I., S. Aust., upper eulittoral (Womersley, 30.viii.1950; ADU, A15398) and from Thompson Creek, St Kilda, S. Aust., upper eulittoral on lower stems of Sarcocornia (Gibbs-Clema, 25.iii.1982; ADU, A52994). The first of these collections has fairly frequent rhizoids 3–5 cells long, while the second is without rhizoids. They are referred to R. tortuosum on cell dimensions but require further study.

Taxonomic notes: R. tortuosum is sometimes included under R. riparium, which is then considered to be variable in cell diameter (e.g. Koster 1955, p. 351; Scagel 1966, p. 74). The southern Australian specimens appear distinct from the slenderer R. riparium or R. implexum.


CHAPMAN, V.J. (1939). Some algal complexities. Rhodora 41, 19–28.

HARVEY, W.H. (1846). Phycologia Britannica. Plates 1–72. (Reeve: London.)

KOSTER, J.Th. (1955). The genus Rhizoclonium Kutz. in the Netherlands. Pubbl. Staz. Zool. Napoli. 27, 335–357.

SCAGEL, R.F. (1966). Marine algae of British Columbia and Northern Washington, Part I: Chlorophyceae (Green Algae). Natl Mus. Can. Bull. 207, i-viii, 1–257.

SETCHELL, W.A. & GARDNER, N.L. (1920b). The marine algae of the Pacific Coast of North America. Part II. Chlorophyceae. Univ. Calif Publ. Bot. 8, 139–375.

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

Author: H.B.S. Womersley

Publication: Womersley, H.B.S. (31 May, 1984)
The Marine Benthic Flora of Southern Australia
Part I
©Board of the Botanic Gardens and State Herbarium, Government of South Australia

Illustration in Womersley Part I, 1984: FIG. 53B, C.

Figure 53 image

Figure 53   enlarge

Fig. 53. A. Rhizoclonium implexum (ADU, A52995). B,C. Rhizoclonium tortuosum. B. Filament with rhizoidal branch (ADU, A15398). C. Filament (ADU, A52994). D. Rhizoclonium riparium (ADU, A52913). E,F. Rhizoclonium curvatum (ADU, A52647). E. Arcuate filament with rhizoids. F. Part of filament with rhizoid.

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