Erythroclonium sedoides (Harv.) Kylin

Scientific Description

Habit and structure. Thallus medium to dark red, 10–25 cm high, much branched above with elongate segments 2–4 mm long and 1–1.5 mm in diameter, branching from their apices; all except uppermost branches becoming heavily thickened (1–2 mm in diameter) and terete, and developing clusters at the nodes of short-stalked, adventitious, clavate segments 1–2(–3) mm long and 0.7–1 mm in diameter. Holdfast discoid, with a single stipe soon becoming branched; epilithic. Structure uniaxial with the axial filament conspicuous throughout, with each axial cell bearing two periaxial filaments at right angles, alternating on adjacent cells, with rhizoids twisted around the axial filament in young segments; medulla with lax periaxial filaments above, becoming filled with rhizoids in thickened branches. Cortex pseudoparenchymatous, 2–3 cells thick in upper segments, 3–6 cells thick in adventitious segments, inner cells ovoid and (10–)15–20 µm in diameter, outer cells 8–16 µm in diameter, L/D 1–2; outer cortical cells in lower branches cutting off files of elongate cells L/D (1–)2–3, 10–20 cells long.

Reproduction.Early sexual reproduction unknown. Cystocarps within the medulla of adventitious segments, with chains of ovoid carposporangia. Tetrasporangia scattered in the cortex of adventitious segments, developed from a mid cortical cell and without outer cortical cells, lying in the cortex and pit-connected basally, ovoid, 40–50 µm long and 20–32 µmin diameter, zonately divided.

Distribution.Dongara to Augusta, W. Aust.

[After Womersley, Mar. Benthic Fl. Southern Australia IIIA: 353 (1994)]