Gelidium crinale (Turner) Gaillon

Scientific Description

Habit and structure. Thallus dark red-brown, forming dense turfs or masses 1–2(–3) cm high and 1–3 cm in spread, with basal stolons, usually short and much branched, bearing erect, slender branches; stolons terete, 100–200 µm in diameter. Erect branches numerous, terete to slightly compressed, of similar dimensions throughout, 100–200(–300) µm in diameter apart from narrower regenerating branches (after grazing?), rather distantly and irregularly branched usually at intervals of 3–10(–15) mm; branch tips tapering fairly abruptly to a point, with a clear apical cell when active. Holdfast of clumped rhizoids from the lower side of stolons, 100–300 µm across; epilithic. Structure. Outer cortical cells rounded in surface view, protoplast 4–8(–10) µm across, wall relatively thin, cortex 3–4 cells thick, medulla 3–6 cells across; rhizines throughout medulla in younger branches, in outer medulla in older branches.

Reproduction.In Australia sexual plants only known in culture. Cystocarps subterminal in clustered branchlets, 500–600 µm across. Stichidia terminal on erect branches or on short laterals near the branch apices, occasionally furcate, slightly to distinctly compressed, 0.5–1.5(–2) mm long, 200–400(–500) µm broad, occasionally with small lateral lobes; in some specimens the branch has continued growth and the stichidium becomes intercalary. Tetrasporangia of varying ages in mixed sori, all around the stichidia, derived from inner cortical cells, ovoid, 20–30(–35) µm in diameter, decussately cruciately divided.

Distribution.British Isles, Europe, and probably widespread in temperate regions. In southern Australia, from Cape Leeuwin, W. Aust., to Point Lonsdale, Vic.

Habitat. G. crinale forms dense turfs where covered by frequent wave-wash or in pools, on coasts of moderate to strong wave action and often subject to sandy conditions. 

[After Womersley, Mar. Benthic Fl. Southern Australia IIIA: 133 (1994)]