s A Field Guide to the British Seaweeds - NMBAQC

Ahnfeltia plicata
Plant completely cylindrical
throughout, very coarse, black and
wiry with narrow fronds of 0.5mm or
less. Branching is highly irregular with
branches very variable in length but
growing up to 15cm long. It is tolerant
of sand cover and tends to be located
in sandy bottomed pools attaching by
a discoid holdfast. It is found in the
lower littoral most commonly in
rockpools.
Audouinella purpurea
Small microscopic plant consisting of
uniseriate filaments. Cells tends to be
longer than broad and are completely
filled with a dense reticulate chloroplast
resulting in a dark pink colour. Branching
is minimal and completely irregular.
Plants tend to be very tangled and are
located within turfs forming a moss on
overhangs and general dark damp areas
throughout the littoral. Not to be confused
with Rhodothamniella floridula.
Typical black wiry form of Ahnfeltia with
close up of cylindrical fronds
Long, narrow cells of
A. purpurea with dense
reticulate chloroplast
Uniseriate filaments of
A. purpurea found in
tangled mats or turfs