s A Field Guide to the British Seaweeds - NMBAQC

Monostroma grevillei
A foliose plant only one layer of cells thick, very
pale green in colour, very thin and membranous
and quite easily torn. Cells with parietal
chloroplast and with one to several pyrenoids,
cells tend to be regularly arranged in packs of two
or four. Broad, flat, fine and delicate leaf-like
morphology with central basal attachment.
Occurs in rockpools mainly on the upper shore
and are most commonly present during the spring
months
Cells arranged in packs of
two or four
Thallus very fine, almost
transparent with open flat form
arising from the splitting of a
primary tubular structure with
central holdfast