Electronic Flora of South Australia Species Fact Sheet

Ulva australis Areschoug 1854: 370.

Phylum Chlorophyta – Order Ulvales – Family Ulvaceae

Selected citations: J. Agardh 1883: 169. Sonder 1881: 39.


U. laeterirens Areschoug 1854: 370. J. Agardh 1883: 167. De Toni 1889: 114. May 1938: 211.

Thallus (Fig. 44B, C) dark green below, lighter above, epilithic or on seagrasses (e.g. Amphibolis), 4–20 (–30) cm high, with several broad fronds from the holdfast, usually much and irregularly divided and lacerate or lobed, 1–6 cm across, margin entire, surface smooth. Cells in surface view arranged in short rows above, soon becoming irregularly arranged (Fig. 45D,E), isodiametric to elongate, 10–20 (–25) µm broad and 20–25 (–30) µm long, basal rhizoid-producing cells larger; pyrenoids 1 (–2) per cell. Thallus 45–60 (–70) µm thick in upper parts (Fig. 45D) with cells in sectional view L/B about 1 (–1.5) and 18–25 µm long, 80–110 µm thick in mid and lower parts (Fig. 45E) with cells L/B 1.5–2 (–2.5) and 22–40 µm long, and (120–) 200–250 (–300) µm thick near the base (Fig. 45F) with a broad central mass of dense rhizoids, with cells L/B 1–1.5 (–2) and 25–40 µm high.

Reproduction: Reproduction not recorded.

Type from Port Adelaide, South Australia, on Amphibolis antarctica; in S. The type sheet consists of four specimens.

Selected specimens: Whitfords Rock (Beach), Perth, W. Aust., 4–5 m deep (Lipkin, 6.ii.1982; ADU, A52961). Port Stanvac, S. Aust., 2 m deep on Amphibolis antarctica (Clarke & Engler, 22.x.1980; ADU, A51817). Rosetta Bay, Victor Harbor, S. Aust., uppermost sublittoral (Womersley, 26.x.1980; ADU, A51819). Sorrento, Vic., lower eulittoral on outer coast (Womersley, 13.i.1981; ADU, A51984). Avoca Beach, N.S.W., in lower eulittoral pools (Womersley, 18.i.1981; ADU, A51983).

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

Distribution: Common in southern Australia, on coasts of strong to moderate wave action, just above and below low tide level, from Whitfords Beach (Perth), W. Aust. to Avoca Beach, N.S.W. and around Tasmania.

Taxonomic notes: U. australis was previously (Womersley 1956, p. 354) placed in synonymy with U. lactuca, but accounts of the latter species by Papenfuss (1960, p. 303, figs 1–3, 10) based largely on the type specimen, and by Bliding (1968, p. 540, figs 1–4) show that the southern Australian plant is specifically distinct. U. australis differs in habit, with several irregularly divided fronds from the base, in cell arrangement (irregular except in upper parts), in thallus thickness (greater, especially in mid and basal parts, where U. lactuca is about 40 µm and 100 p.m thick respectively, c.f. Bliding) and in cell size where U australis cell dimensions considerably exceed those given by Bliding for U. lactuca, both for surface view and also for sectional dimensions. The base of U. australis is more strongly developed with a much thicker central rhizoidal region than is usual in U. lactuca. J. Agardh (1883, p. 169) placed U. australis tentatively under U. rigida, and while in thickness and cell dimensions it is similar to this species, it does not have the microscopic, marginal spines of U. rigida and the cells of U. australis are more angular and do not taper outwardly in transection of the thallus.

Phycoseris ulva Sonder (1845: 49; 1846: 153) from W. Aust. (Preiss) may be the same as Ulva australis but the Preiss specimen in MEL (608403) does not fully agree with Sonder's description and other Preiss material should be examined.

Ulva laetevirens Areschoug, from Port Phillip, Vic., comprises two specimens in Herb. Areschoug, S ; one, with a single, large, expanded and lacerate frond, has been selected as lectotype. The cells do not show the characteristics of U. rigida and the lectotype appears to be a large, single frond with the cell dimensions and proportions of U. australis. U. laetevirens was recorded from around New Zealand by Chapman (1956, p. 393).

U. australis occurs under strong to moderate water movement, whereas U. lactuca in Sweden and also as recognized in southern Australia is found in more sheltered waters. Some of the above differences might be expected between plants in rough-water and sheltered habitats, and it is highly desirable that crossing experiments be carried out between these species.


AGARDH, J.G. (1883). Till algernes systematik. VI. Ulvaceae. Acta Univ. lund. 19(2), 1–182, Plates 1–4.

ARESCHOUG, J.E. (1854). Phyceae novae et minus cognitae in maribus extraeuropaeis collectae. Acta R. Soc. Sci. Upsala, Ser. III, 1, 329–372.

BLIDING, C. (1968). A critical survey of European taxa in Ulvales, II. Ulva, Ulvaria. Monostroma, Kornmannia. Bot. Notiser 121, 535–629.

CHAPMAN, V.J. (1956). The marine algae of New Zealand. Part I. Myxophyceae and Chlorophyceae. J. Linn. Soc. Bot. 55 (360), 333–501, Plates 24–50.

DE TONI, G.B. (1889–1924). Sylloge Algarum omnium hucusque Cognitarium. Vols 1–6. (Padua.)

MAY, V. (1938). A key to the marine algae of New South Wales. Part I. Chlorophyceae. Proc. Linn. Soc. N.S. W. 63, 207–218.

PAPENFUSS, G.F. (1960). On the genera of the Ulvales and the status of the order. J. Linn. Soc. Bot. 56, 303–318, Plates 1–6.

SONDER, O.W. (1845). Nova algarum genera et species quas in itinere ad oras occidentales Novae Hollandiae, collegit L. Preiss, Ph.Dr. Bot. Ztg 3, 49–57.

SONDER, O.W. (1846). Algae. In C. Lehmann, Plantae Preissianae. Vol. 2, pp. 148–160. (Hamburg.)

SONDER, O.W. (1881). In F. Mueller, Fragmenta Phytographiae Australiae. Supplementum ad volumen undecinum: Algae Australianae hactenus cognitae. pp. 1–42, 105–107.

WOMERSLEY, H.B.S. (1956). A critical survey of the marine algae of southern Australia. I. Chlorophyta. Aust. J. mar. freshw. Res. 7, 343–383.

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

Illustrations in Womersley Part I, 1984: FIGS 44B, C, 45 D–F.

Figure 44 image

Figure 44   enlarge

Fig. 44. A. Ulva lactuca (ADU, A42338). B. Ulva australis, on Amphibolis (ADU, A51817). C. Ulva australis (ADU, A51819). D. Ulva rigida (ADU, A51821).

Figure 45 image

Figure 45   enlarge

Fig. 45. A–C. Ulva lactuca (ADU, A52029). A. Surface and cross section views of young thallus. B. Ditto, of mid thallus. C. Ditto, rhizoidal region near base. D–F. Ulva australis (ADU, A51819). D. Surface and cross section views of young thallus. E. Ditto, of mid thallus. F. Cross section view of rhizoidal region near base. G–J. Ulva rigida (ADU, A51816). G. Thallus margin with spines. H. Cross section view of young thallus. I. Surface and cross section views of mid thallus. J. Surface view of rhizoidal region near base.

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