Stems with 5-9 rounded, prominent ridges, small stem-cavity. Loose grey-green sheaths, white-edged black teeth. Irregular whorls of hollow branches with short lower internodes.
Permanently damp and base-rich grassland, ditches, marshes. Most frequent in the north of Ireland.
Identification uncertain: Photographs probably Field Horsetail, Equisetum arvense. Correction by Paul Green
Marsh Horsetail. The Gearagh, Co.Cork. April 2008