Cartilaginous, usually markedly compressed, dark purple to pale yellow fronds, to 100 mm or more long, from discoid base. Very variable in size and form. Main axis usually simple, branching alternate distichous, repeatedly pinnate. Ultimate ramuli short, blunt.

A small red alga (up to 8 cm in length), it is tough and cartilaginous with flattened fronds. Branching is alternate and occurs in one plane only, with branches becoming shorter towards their apex and broadly rounded. The plant is highly variable in size and colouration depending upon its location on the shore. Higher shore plants are generally dwarfed and yellow-green in colour, owing to exposure to high levels of sunshine while on the lower shore they are reddish-brown.

Key characteristics: Plants degenerate soon after collection, are more brittle than O. osmunda and O. truncata.

Similar species: Laurencia osmunda is larger and arises from spreading stolons. Osmunda truncata is less common, is more pinnately branched, generally grows epiphytically, and rapidly degenerates on collection; it is sometimes locally abundant (e.g., in the inner part of Lough Hyne, Co. Cork).

Loiseaux-de Goër, S. & Noailles, M.-C. (2008). Algues de Roscoff. pp. [1]-215, col. figs. Roscoff: Editions de la Station Biologique de Roscoff.

Maggs, C.A. & Hommersand, M.H. (1993). Seaweeds of the British Isles. Volume 1. Rhodophyta. Part 3A. Ceramiales. pp. xv + 444, 129 figs, map. London: HMSO.

Nam, K.W., Maggs, C.A. & Garbary, D.J. (1994). Resurrection of the genus Osmundea with an emendation of the generic delineation of Laurencia (Ceramiales, Rhodophyta). Phycologia 33: 384-395, 38 figs, 3 tables.

Serio, D., Petrocelli, A., Cormaci, M., Cecere, E. & Furnari, G. (2008). First record of Osmundea oederi (Gunnerus) G. Furnari comb. nov. (Rhodomelaceae, Rhodophyta) from the Mediterranean Sea. Cryptogamie, Algologie 29: 119-127.

Wynne, M.J., Serio, D., Cormaci, M. & Furnari, G. (2005). The species of Chondrophycus and Laurencia (Rhodomelaceae, Ceramiales) occurring in Dhofar, the Sultanate of Oman. Phycologia 44: 497-509.

In English: Pepper Dulse

In Portuguese: Erva malagueta

Basionym: Fucus pinnatifidus Hudson

Type locality: Harwich, Essex, England (Silva, Basson & Moe 1996: 534). Notes: This type locality was first recorded by Maggs & Hommersand (1993: 403, footnote).