Myriodesma integrifolium Harv.

Scientific Description

Habit and structure. Thallus medium to dark brown, (10–)20–40 cm long, with 2–3 essentially complanately branched fronds from each branch of the stipe. Holdfast discoid-conical, 2–10 mm across; epilithic. Stipe 2–10 cm long, with 1–5 di- or trichotomies at intervals of 2–6 cm, each 1–3 mm in diameter. Fronds 15–30 cm long, pinnate becoming bipinnate, alternately branched with branches 2–4(–5) mm broad, linear and usually serrate at least above, occasionally almost entire, basally slightly constricted; midrib conspicuous below, inconspicuous above. Growth from a three-sided apical cell in an apical depression. Structure of fronds 300–400µm and 8–12 cells thick, with a medulla of elongate cells and a cortex of isodiametric cells with an inactive surface meristoderm of short cells.

Reproduction. Thalli monoecious. Conceptacles densely scattered over upper branches, with a narrow sterile margin, bisexual, with a basal tuft of phaeophycean hairs; oogonia sessile, ovoid, 50–80 µmlong and 40–50 µm in diameter; antheridia sessile or on branched paraphyses, elongate-ovoid, 20–35 µmlong and 10–15 µm in diameter.

Distribution.From Cottesloe, W. Aust., to Western Port, Vic. and the N coast of Tas.

Habitat. M. integrifolium is essentially a deep water eastern species, drift specimens being not uncommon on S. Aust., Vic. and N Tas. coasts.

[After Womersley, Mar. Benthic Fl. Southern Australia II: 412 (1987)]