The spores differ from those of ferns in their outer coat (exospore) being split up into four club-shaped hygroscopic threads (elaters) which are curled when moist, but become straightened when dry.
Club-shaped hydranths with numerous tentacles, generally scattered irregularly, sometimes with a spiral arrangement, or in whorls (" verticillate ").
Bases of the rhinophores surrounded by a sheath; dorsal papillae tuberculated and club-shaped, in a single row on either side of the dorsum; no cnidosacs.
The seeds or grape-stones are somewhat club-shaped, with a narrow neck-like portion beneath, which expands into a rounded and thickened portion above.
Cercospora Vitis (Cladosporium viticolum), which has club-shaped spores of a green-brown colour, also attacks the leaves; but, unless the season is extremely unfavourable, it does little harm.