Ceramium cimbricum

Thalli fine filamentous, bushy, 0.5–3.5(–10) cm high, purple to dark red. Branching irregularly dichotomous, with straight or slightly incurved apices. Internodes 50–160 μm diam., 150–250(–500) μm long, striated, lightly pigmented. Nodes 50–170 μm diam., 30–60 μm long., swollen, heavily pigmented, composed of two cell layers in young plants: upper layer of small cells, ~7.5 μm diam., lower layer of large cells, 17–20×25 μm; and 4–6 rows in old thalli with small upper cells and larger ones in lower rows. Sporangia prominent, spherical, tetrahedrally divided, to 65 μm diam, solitary or in rows at nodes. Attachment by unicellular rhizoids issuing from nodes of creeping axes. Growing on hard substrate, epiphytic on larger algae, in low intertidal, upper subtidal, in sheltered and semi-protected coasts.

Europe. Atlantic, Indian and Pacific Oceans.