Gelidium crinale

Thallus bushy, cartilaginous, dark redbrown, forming dense turfs or masses, 2–4(–6) cm high, composed of prostrate axes, bearing erect branches. Prostrate axes terete, 100–200 μm diam. Erect axes numerous, terete at base, slightly compressed above, 220×330 μm, with acute apex, branching pinnate, alternate, rarely opposite. Cells from the surface roundish, ~8 μm across, with thin walls. In transverse section, cortex consists of 1–2 layers of small cells, 6–7.5×10 μm. Medullary cells 15–22.5 μm diam., thickwalled, surrounded by small cells (5–7.5 μm diam.) of rhizoidal filaments, except outer cells of medulla. Cystocarps form at the ends of branches, 500–600 μm in diam. Tetrasporangia ovoid, 22.5–30×27–35 μm, cruciately divided; develop in cortical layer of swollen apical portion of branches with lanceolate or spatulate appearance.

Temperate and subtropical latitudes.