Cystophora subfarcinata (Mert.) J.Agardh

Scientific Description

Habit and structure. Thallus medium to dark brown, young plants often light brown, 20–80 cm (–2 m) long, with primary and often long secondary axes bearing dense, lateral, tufts of ramuli. Holdfast discoid-conical, 3–12 mm across, with a single, short, subterete stipe; epilithic. Primary axes compressed, 2–7 mm broad and 1–2(–3) mm thick, with narrow edges, slightly flexuous, distichously branched from the face with dense, usually short, secondary axes (1–)2–8 cm long; secondary (and tertiary) axes slightly retroflex, densely and distichously branched, often basally denuded with short, close-set residues. Laterals simple to (usually) irregularly alternately branched, not in one plane; ramuli terete, simple or branched, (0.5–)1–3 cm long and 0.4–0.7 mm in diameter. Vesicles absent (in rough-water forms) or present and usually abundant, replacing the basal ramulus of a lateral, petiolate, elongate-ovoid to subspherical, mutic, 2–4(–6) mm long, 2–3(–4) mm in diameter.

Reproduction. Thalli monoecious. Receptacles simple or often branched, (0.5–)1–3(–5) cm long, 1–2 mm thick at conceptacles, with prominent, swollen, irregularly placed conceptacles, often a few near the base more or less in two rows, usually with sterile tissue between the conceptacles and a prominent sterile awn. Conceptacles bisexual or occasionally unisexual, with ostioles scattered or in two rows near the base, with simple paraphyses; oogonia sessile, ovoid, 80–120 µmlong and 50–70 µmin diameter; antheridia sessile or on branched paraphyses, ovoid, 25–35 µmlong and 14–16 µmin diameter.

Distribution. From Nickol Bay, W. Aust., to Wilsons Promontory, Vic., and around Tas.

Habitat. C. subfarcinata is probably the commonest species of Cystophora on southern Australian coasts, in shallow water (to about 5 m deep) under conditions of strong to moderate wave action; vesicles are not formed on plants on rough-water coasts.

[After Womersley, Mar. Benthic Fl. Southern Australia II: 400 (1987)]