Pelvetia

Lore & Background

Pelvetia canaliculata grows in dense tufts up to 15 cm long, with fronds deeply channeled on one side. These channels, along with a mucus layer, help prevent desiccation during low tide. The alga is irregularly dichotomously branched, dark brown, and lacks a midrib, air vesicles, and cryptostomata. Its reproductive organs form swollen, irregularly shaped receptacles at the branch tips, which are hermaphrodite and borne within conceptacles at the apices. The receptacles become yellowish-green at maturity during summer.

Reader's Guide

Pelvetia canaliculata is ecologically significant as the only large alga forming a distinct zone on the upper littoral fringe of European Atlantic shores, from Iceland to Portugal. It tolerates a wide range of exposure but requires periods of air exposure; submersion for more than six hours out of twelve leads to decay. It grows so high on the shore that coarse grass and other angiosperms sometimes grow among it. In Ireland, it was historically collected as a food source during famines, and is referenced in the folk song 'Dúlamán'. Its taxonomic history is notable: in 1999, all other species formerly in Pelvetia were moved to the genus Silvetia based on oogonium structure and rDNA sequences, leaving Pelvetia monotypic. The genus was named after French naturalist François Alexandre Pelvet and circumscribed by Decaisne and Thuret in 1845.

Did You Know?

• Pelvetia canaliculata is the only species remaining in the genus Pelvetia after other members were reclassified as Silvetia in 1999.
• The genus was named in honor of French naturalist and plant collector François Alexandre Pelvet (1801–1882).
• It grows at or above the high-water mark and begins to decay if submerged for more than six hours out of twelve.
• In Ireland, collection of Pelvetia canaliculata (Irish: dúlamán) was recorded as a food source during famines.