Stypocaulon scoparium (Linnaeus) Kützing

Stypocaulon scoparium © M.D. Guiry

Description: Frond filiform, dark brown stiff tufts, to 150 mm long, attached rhizoids.  Filaments segmented, each segment with 1-3 longitudinal divisions and occasional secondary transverse divisions.  Branching abundant, irregularly alternate and pinnate; lateral branches straddling cross wall between two articulations.  Filaments often densely packed giving from an appearance of a series of inverted cones,  shaving-brush like.  Lower parts of main axes often bare. Unilocular sporangia formed in clusters on short branchlets in the axils of main branches; plurilocular sporangia rare.
Habitat: Infralittoral epilithic, particularly in sandy pools. Uncommon on southern and western coasts, rarer further north.