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Electronic Flora of South Australia Species Fact Sheet

Sargassum linearifolium (Turner) C. Agardh 1820: 24; 1824: 303.

Phylum Phaeophyta – Order Fucales – Family Sargassaceae

Selected citations: J. Agardh 1848: 296; 1872: 57; 1889: 45 (in part only, excl. figs). De Toni 1895: 11. Kützing 1849: 612; 1861: 6, pl. 18a,b. Womersley 1954b: 352.


Focus linearifolius Turner 1809: 106, pl. 111.

Sargassum merrifieldii J. Agardh 1889: 115, pl. 30 figs 13–17. Grunow 1916: 159. Lucas 1936: 68.

Thallus (Fig. 165) dark brown, 10–50 cm long, with a simple stipe 1–3 (–6) cm long, more or less terete, 2–3 mm in diameter, with rounded branch residues, bearing apically and radially 2–4 (–6) primary branches. Holdfast discoid-conical, 3–15 (–30) mm across, bearing 1–6 (or more) stipes. Primary branches 10–45 cm long, densely covered throughout their length with short secondary branches 2–5 cm long and bearing slender, linear, laterals and crowded tufts of receptacles when mature; branch axes terete to angular, sometimes with short spines, radially branched. Laterals (lower) 3–8 (–10) cm long, (2–) 3–5 (–8) mm broad, relatively thick, simple or rarely furcate, linear to lanceolate, entire or with occasional small spines, costate, usually with prominent scattered cryptostomata; upper laterals 1.5–8 cm long, 1–2 (–3) mm broad, linear, entire or occasionally with a few spines. Vesicles axillary, petiolate, subspherical to slightly ovoid, 3–5 mm in diameter, mutic or rarely mucronate.

Reproduction: Thalli monoecious. Receptacles (Fig. 168B,C) unisexual or bisexual, forming dense clusters 3–10 mm long, much branched (Fig. I68C) furcately or laterally, terete, 0.6–1.2 mm in diameter, drying slightly verrucose, apices rounded, with scattered ostioles. Conceptacles unisexual; oogonia sessile, ovoid to subspherical, (100–) 160–240 µm long and (60–) 90–220 µm in diameter, few per conceptacle; antheridia sessile or on short, branched, paraphyses, ovoid, (18–) 20–28 µm long and (8–) 10–18 µm in diameter.

Type from "western coast of New Holland" (probably King George Sound, W. Aust.) (Menzies); in BM (ex K).

Selected specimens: Port Denison, W. Aust., inner reef pools (Gordon, 8.xi.1968; ADU, A33224). North Beach, Perth, W. Aust., upper sublittoral (Woelkerling, 14.xi.1968; ADU, A34085). Cape Naturaliste, W. Aust., uppermost sublittoral (Womersley, Clarke & Engler, 2.ix.1979; ADU, A50624). Head of the Great Australian Bight, S. Aust., drift (Gordon, 4.xi.1968; ADU, A34191). Port Willunga, S. Aust., upper sublittoral pools ( Womersley, 12.x.1953; ADU, A19095). Aldinga, S. Aust., 1–5 m deep off reef (Lewis, 7.xii.1972; ADU, A42896-"Marine Algae of southern Australia" No. 296). Ballast Head, Kangaroo I., S. Aust., upper sublittoral, east side ( Womersley, 28.xii.1948; ADU, A10460). Pennington Bay, Kangaroo I., S. Aust., reef pools (Womersley, 31.i.1957; ADU, A20778). The Bluff, Victor Harbor, S. Aust., 3 m deep (Scott, 11.ix.1986; ADU, A57169). Robe, S. Aust., upper sublittoral pools (Womersley, 20.xii.1953; ADU, A19142). Point Roadknight, Vic., drift (Sinkora A1456, 29.xi.1971; ADU, A43109). Point Nepean, Vic., lower eulittoral pool (Price, 9.xii.1963; ADU, A27051). Pebbly Beach, 20 km N. of Batemans Bay, N.S.W., upper sublittoral pools (Womersley, 15.i.1964; ADU, A27415). Cronulla, N.S.W., upper sublittoral ( Womersley, 18.viii.1959; ADU, A23075).

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

Distribution: From Port Denison, W. Aust., around southern Australia to N.S.W.; doubtfully from the N. coast of Tasmania.

Taxonomic notes: Sargassum linearifolium is the most widely distributed southern Australian species of subgenus Sargassum, and is often common in rock pools or the uppermost sublittoral on coasts of strong to moderate water movement. It is characterised by its dark brown colour, the profuse, narrow, linear, upper laterals, and dense, much branched, clusters of terete receptacles. The occasionally branched laterals are present on most but not all plants. The species was excluded from Phyllotrichia by Womersley (1954, p. 352), who suggested that it might be better placed in Arthrophvcus. However, the lack of large basal laterals and also of triquetrous branch axes suggest that it is best referred to subgenus Sargassum, although the laterals are much darker brown than is usual in this subgenus.

The type locality is likely to be King George Sound, W. Aust., since this is the only south-western Australian locality visited by Menzies on the 'Vancouver' expedition. Some later records are clearly incorrect. Most specimens in Herb. Agardh, LD, under S. linearifolium are S. sonderi, as are J. Agardh's figures (1889, pl. 14 figs 3–7). The brief description of May (1939, p. 202) similarly does not agree with S. linearifolium.

S. merrifieldii J. Agardh is based on specimens from Adelaide, S. Aust. (Merrifield) and Israelite Bay, W. Aust. (Mueller), of which the former in Herb. Agardh, LD (3123) is chosen as lectotype. They agree well with S. linearifolium. The record of S. merrifieldii of Chauhan & Thivy (1965, p. 69) from India is probably not of this species.

The receptacles of S. linearifolium are similar to mature, branched, receptacles of S. spinuligerum. These two species are usually clearly distinguished on colour, dimensions and form of the laterals, but a few possible intergrades do occur.


AGARDH, C.A. (1820). Species Algarum. Vol. 1, Part 1, Fucoideae, pp. 1–168. (Lund.)

AGARDH, C.A. (1824). Systema Algarum. (Lund.)

AGARDH, J.G. (1848). Species, Genera et Ordines Algarum. Vol. 1. (Gleerup: Lund.)

AGARDH, J.G. (1872). Till algernes systematik. Ada Univ. lund. 9(8), 1–71.

AGARDH, J.G. (1889). Species Sargassorum Australiae. K. Svenska Vetenskapsakad. Handl. 23(3), 1–133, Plates 1–31.

CHAUHAN, V.D. & THIVY, F. (1965). Sargassum merrifieldii J. Ag. new to the shores of India. Phykos 4, 69–70.

DE TONI, G.B. (1895). Sylloge Algarum omnium hucusque Cognitarum. Vol. 3. Fucoideae. pp. 1–638. (Padua.)

GRUNOW, A. (1916). Additamenta ad cognitionem Sargassorum. Verh. Zool. -Bot. Gesell. Wien 66, 136–185.

KÜTZING, F.T. (1849). Species Algarum. (Leipzig.)

KÜTZING, F.T. (1861). Tabulae Phycologicae. Vol. 11. (Nordhausen.)

LUCAS, A.H.S. (1936). The Seaweeds of South Australia. Part 1. Introduction and the Green and Brown Seaweeds. (Govt Printer: Adelaide.)

MAY, V. (1939). A key to the marine algae of New South Wales. Part. II. Melanophyceae (Phaeophyceae). Proc. Linn. Soc. N.S.W. 64, 191–215.

TURNER, D. (1809). Fuci sive Plantarum Fucorum Generi a Botanicis Ascriptarum Icones Descriptiones et Historia. Vol. 2, pp. 1–162, Plates 72–134. (London.)

WOMERSLEY, H.B.S. (1954b). Australian species of Sargassum, subgenus Phyllotrichia. Aust. J. Bot. 2, 337–354, Plates 1–5.

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

Author: H.B.S. Womersley & L.A. Scott

Publication: Womersley, H.B.S. (14 December, 1987)
The Marine Benthic Flora of Southern Australia
Part II
©Board of the Botanic Gardens and State Herbarium, Government of South Australia

Illustrations in Womersley Part II, 1997: FIGS 165, 168B,C.

Figure 165 image

Figure 165   enlarge

Fig. 165. Sargassum hnearifohum A. (ADU, A19142). B. (ADU, A50624).

Figure 168 image

Figure 168   enlarge

Fig. 168. Receptacles of species of Sargassum. A. Sargassum lacerifolium (ADU, A55356), triquetrous receptacles. B,C. Sargassum linearifolium (B, ADU, A19095; C, ADU, A34191). B. Young receptacles. C. Mature receptacles. D. Sargassum spinuligerum (ADU, A39204). E. Sargassum podacanthum (ADU, A24690). F. Sargassum distichum (ADU, A24363).

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