Fucus spiralis

Fucus spiralis is a species of seaweed, a brown alga (Heterokontophyta, Phaeophyceae), living on the littoral shore of the Atlantic coasts of Europe and North America.

It grows to about 30 cm long and branches somewhat irregularly dichotomous and is attached, generally to rock, by a discoid holdfast.

[1][2] The reproductive bodies form rounded swollen tips on the branches, usually in pairs.

These three species, along with two others Pelvetia canaliculata and Ascophyllum nodosum form the zones along the shore.

Fucus spiralis produces phlorotannins of both the fucol and fucophlorethol types.

In this photograph of a horizontal cutting of the lower part of the blade (under an optic microscope) we can distinguish very well the medulla, the cortex and the meristoderm of F. spiralis . We can also see, by the disposition of the cells, some specialization and formation of proto-tissues.
Fucus spiralis var. platycarpus