s A Field Guide to the British Seaweeds - NMBAQC

Ulothrix sp.
Plant consisting of long unbranched filaments
bright green in colour. Cells usually much shorter
than broad or may be equal length and breadth,
approximately 10-30um, with a single band
shaped parietal chloroplast covering about ¾ of
the inner cell wall, pyrenoids (one to many) often
visible within the chloroplast. Ulothrix present in a
number of morphologies with wide or narrow
filament wall and filament width variable and as
straight or curled filaments often as a result of
reproductive bodies. Plants may be found in turfs
on rock surfaces or commonly found growing
epiphytically on Fucus species where microscopic
identification is required to distinguish from
Blidingia and other filamentous species known to
grow on Fucus. May be confused with Urospora
sp. which have larger barrel shaped cells.
Filaments either straight or curled up
forms may also be found together
Filaments with thin or
thick walls, cells wide
and flat or broad and
pyrenoids often clearly
Ulothrix often found
visible
growing on Fucus sp.