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Electronic Flora of South Australia Species Fact Sheet

Myriodesma leptophyllum J. Agardh 1890: 6.

Phylum Phaeophyta – Order Fucales – Family Cystoseiraceae

Selected citations: Nizamuddin & Womersley 1967: 375, pls 69A, 73 fig. 1.


Scaenophora australis J. Agardh 1899: 155.

Thallus (Fig. 151A) medium to dark brown, 10–30 cm long, with 2–3 more or less complanately branched fronds from each branch of the stipe. Holdfast discoid-conical, 3–10 mm across; epilithic. Stipe 5–15 cm long, irregularly branched at intervals of 2–10 cm, each 1–3.5 mm in diameter, thickening by meristoderm activity. Fronds 3–20 cm long, pinnate becoming bipinnate, laterals sub-opposite below, alternate above, compressed, linear, entire, 0.5–1.5 mm broad; midrib absent or slight. Structure of fronds 300–400 µm and 10–15 cells thick, with a slight medulla of elongate cells and hyphae, and a cortex of isodiametric cells with an inactive surface meristoderm of short cells.

Reproduction: Thalli monoecious. Conceptacles in a single, occasionally double, irregular row on each side of the branches (Fig. 155C), bisexual, with a dense basal tuft of phaeophycean hairs; oogonia sessile, ovoid but broad-based, 100–120 µm long and 50–80 µm in diameter; antheridia sessile or on short, branched, paraphyses, ovoid, 20–30 µm long and 8–12 µm in diameter.

Type from Israelite Bay, W. Aust. (Brooks); in Herb. Agardh, LD, 2385.

Selected specimens: Near Isles of St Francis, S. Aust., 37 m deep (Symonds, 23.x.1973; ADU, A44247). Encounter Bay, S. Aust. (Hussey; Herb. Agardh, LD, 993). Robe, S. Aust., drift (Womersley, 16.xii.1986; ADU, A57326).

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

Distribution: From Israelite Bay, W. Aust. to Robe, S. Aust.

Taxonomic notes: M. leptophyllum is a rare but distinctive species, with slenderer fronds than any other species; however, relationships with slender forms of M. integrifolium need further study.


AGARDH, J.G. (1890). Till algernes systematik. Ada Univ. lund. 26(3), 1–125, Plates 1–3.

NIZAMUDDIN, M. & WOMERSLEY, H.B.S. (1967) The morphology and taxonomy of Myriodesma (Fucales). Nova Hedwigia 12, 373–383, Plates 69–73.

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

Author: H.B.S. Womersley

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 151A, 155C.

Figure 151 image

Figure 151   enlarge

Fig. 151. A. Myriodesma leptophyllum (ADU, A57326). B. Myriodesma serrulatum (ADU, A51221).

Figure 155 image

Figure 155   enlarge

Fig. 155. A. Platythalia quercifolia (ADU, A30788). End of a lateral branch with scattered conceptacles. B. Platythalia angustifolia (ADU, A30988). Apex of a branch with laterals containing submarginal conceptacles. C. Myriodesma leptophyllum (ADU, A57326). Upper branches with conceptacles. D. Myriodesma serrulatum (ADU, A51221). Upper branches with raised conceptacles. E. Myriodesma integrifolium (ADU, A57457). Upper branches with conceptacles.

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