- Reference
- Austral.J.Bot.Suppl.Ser. 35 (1972)
- Conservation Code
- Not threatened
- Naturalised Status
- Native to Western Australia
- Name Status
- Current
Scientific Description
Habit and structure. Thallus medium to dark red-brown, 10–22 cm high, largely complanately and alternately branched with long laterals 0.5–1 mm in diameter, fringed with short lateral branchlets 1–3 mm long surrounded by a tuft of filaments; lower branches 2–5 mm in diameter. Holdfast 2–6 mm across, rhizoidal; epilithic. Structure. Apical and subapical cells small, enlarging gradually to 200–250 µm in diameter and to 500 µm long near the base. Each subapical cell cutting off 5 periaxial cells in alternating sequence, developing into pseudodichotomous whorl-branchlets 2–4 mm long, branched 5–6 times, median cells 45–65 µm in diameter and L/D 1.5–2(–3), terminal cells mucronate; first and second whorl-branchlets become villose and alternately pinnate, forming the terminal tufts on the short lateral branches. Indeterminate lateral branches arise from the basal cells of second-formed whorl-branchlets and are thus distichous on alternate sides of the main branches. Cortication by descending rhizoids from the basal cells of whorl-branchlets, developing below an outer cortex of branched anticlinal filaments 45–60 µm in diameter with subspherical terminal cells 90–125 µm in diameter; lower axes often denuded of whorl-branchlets in older plants, leaving only the cortex of anticlinal filaments. Cells uninucleate; rhodoplasts discoid.
Reproduction. Gametophytes dioecious. Procarps formed as in W. nobilis, carpogonial branches 4-celled (rarely 5-celled), formed on successive subapical cells. Carposporophyte with intermixed sterile whorl-branchlets, the whole 1–1.8 mm across, carposporangia clavate, 45–120 µm in diameter. Spermatangial heads subspherical, 100–180 µm in diameter, borne on 1–2-celled stalks on lower cells of the whorl-branchlets on young indeterminate branches with much reduced involucral branches 1–2 cells long on the stalk cell. Tetrasporangia are terminal on 1–3-celled stalk cells on the lower 1–2 cells of whorl-branchlets, with short, curved, involucral branches on the stalk cell; sporangia 120–140 µm in diameter, tetrahedrally divided.
Distribution. Eucla, W. Aust., to Kingston, S. Aust.
Habitat. W. australis appears to be a deeper water alga on moderate to rough-water coasts.
[After Womersley, Mar. Benthic Fl. Southern Australia IIIC: 33–37 (1998)]