s A Field Guide to the British Seaweeds - NMBAQC

Group A
1. Plant calcareous……………………………………………………………...2
1. Plant non-calcareous forming a deep red staining on the rock surface
Hildenbrandia rubra
2. Plant appearing filiform, consisting of a jointed calcareous upright system
resembling small bones and generally located in rockpools
Corallina officinalis
2. Plant forming a small or large crust or layer over the surface of rocks and
other algae……………………………...………..…………………………….3
3. Plant microscopic appearing as a small disc of radiating cells present on a
number of red algal species and hydroids Melobesia membrancea
3. Plant forming large crust over the rock surface, consisting of various textures
and shades or pink, purple and red, may also be found covering the outer
frond of algal species such as Polyides Calcareous encrusters
Group B
1. Plant with midrib or veins present………………………………………...…..2
1. Plant without midrib or veins………………………………………………….5
2. Plant with distinct midrib…………………………………………………...…3
2. Plant with indistinct, faint and interrupted midrib, blade quite wide and leafy
but with course cylindrical stipe Phyllophora sp.
2. Plant without a midrib but with macro/microscopic veins present, blade edges
often frilly and tatty looking with disc holdfast Cryptopleura ramosa
Reduced species list identification guide as required by the Water Framework Directive 32