Osmundea hybrida (Hudson) K.W. Nam
Also known as Laurencia hybrida (A.P. de Candolle) Lenormand ex Duby
Description: Cylindrical, cartilaginous, tufted, dark purple to greenish yellow fronds, 150 mm long. Main axis with repeatedly pinnate branching, branches mostly alternate, shorter towards apex giving pyramidal outline. Ultimate ramuli short, patent, truncate.
Habitat: On stones and limpets in pools, occasionally on mussels on open rock, rarely epiphytic, often forming a turf in damp crevices, particularly common in upper intertidal, widely distributed, locally abundant.
Key characteristics: Terete thallus, discoid holdfast.
Similar species: Osmundea truncata, which also has a discoid holdfast but is distinctly compressed in the upper parts, and is generally found growing epiphytically.
Photographs © M.D. Guiry