About Delesseria sanguinea (Hudson) J.V.Lamouroux
Delesseria sanguinea (Hudson) J.V.Lamouroux is a common, bright red perennial alga. It grows flat, leaf-like red blades from a discoid holdfast. Each blade is monostromatic, meaning it is made of a single layer of cells, and can grow up to 25 cm long and 8 cm wide. Each blade grows from a cylindrical, stalk-like stipe that only branches near its base. Blades have a visible central midrib with lateral veins, and their tips are rounded. Several similar algae exist: Apoglossum ruscifolium, Hypoglossum hypoglossoides, and Membranoptera alata are all much smaller than Delesseria sanguinea. Phycodrys rubens reaches a comparable size, but is easily distinguished by the lobed edges of its blades. This alga grows on rock in pools at low water, and also grows in sublittoral zones down to 30 m deep as an epiphyte on other large algae. It is common around Ireland, Great Britain, the Isle of Man, and the Channel Islands, ranging north to Norway and Iceland, and south to Spain. All reproductive bladelets of this alga form on the midrib. Male reproductive bladelets reach 6 mm long. Spermatangial sori develop on both sides of the blade's midrib, forming a continuous, oval-shaped sorus on the blade. Female bladelets have a narrow lamina, and cystocarps form near the apex on a short stalk. Tetrasporangial bladelets are oval-shaped and grow up to 4 mm in size.
