Alaria esculenta (Linnaeus) Greville

Description: Plants with olive or yellow-brown fronds to 4 m long and 25 cm wide. Attached by a root-like holdfast at the base from which a narrow flexible stipe arises which continues into the leafy part of the plant as a distinct mid-rib. The reproductive structures, apparent as dark-brown areas, are confined to unbranched leafy appendages borne on the stripe, usually in two rows.

Habitat: Generally growing on rock in very exposed places, often forming a band at low water and in the shallow subtidal, but also occurring in tidal pools in the lower shore.

Distinguishing features: This is the only kelp-like plant in Ireland and Britain with a distinct midrib and is the only one with sporangia borne at the base of the frond in special leaflets called sporophylls.