Delesseria sanguinea

Delesseria sanguinea is a common and bright red perennial alga with flat leaf-like red blades rising from a discoid holdfast. The blades are monostromatic, that is composed of a layers of single cells, and can grow to 25 cm long. Each blade rises from a cylindrical stipe, the stalk-like part, which branches only at near the base. Each blade may 8 cm wide and show a clear midrib with lateral veins. The tips of the blades are rounded.[1][2] Other similar algae include: Apoglossum ruscifolium, Hypoglossum hypoglossoides and Membranoptera alata all of which are much smaller.[2] Phycodrys rubens is of comparable size but can be easily distinguished having lobed edges to the blades.[2]

All reproductive bladelets are formed on the midrib.[1] Male reproduction bladelets and reach 6 mm long. Spermatangial sori develop on both sides of the midrib on the blade are form a continuous sorus on the blade, oval in shape. Female bladelets have a narrow lamina and cystocarp forms near the apex on a short stalk. Tetrasporangial bladelets are oval in shape and up to 4 mm in size.[1]

Growing on rock in pools at low water and also sublittoral to 30 m deep epiphytic on other large algae.[1][2]

Common around Ireland, Great Britain, Isle of Man, Channel Islands, to the north to Norway and Iceland south in Spain.[2]

• Dickinson, C.I. 1963 British Seaweeds. The Kew Series. Eyre & Spottiswoods
• Morton, O. 1994. Marine Algae of Northern Ireland. Ulster Museum.ISBN 0-900761-28-8
• Morton, O. 2003. The marine macroalgae of County Donegal, Ireland. Bulletin of Irish biogeographical Society No 27.