Thallus up to 30-40 cm, thick, spongy and round axes, and normally dichotomously branched Codium fragile
Thallus different 2
Thallus very small (normally < 1 cm and max. 3-4 cm) and in high intertidal often on resting places for sea birds, cells arranged in lines 4
Thallus relatively big (several cm long) and not high in the intertidal 5
Thallus blade-formed, < 1 cm and narrowing to a short stipe, cells arranged in groups Prasiola stipitata
More rare, also terrestrial and also on additional substrate than rock:
– Thallus to 3-4 cm, often curly edge and lacking stipe Prasiola crispa
– Thallus smaller and rounded, stipe short or absent, blade curled at edge, cells arranged in groups, sometimes conspiciuous separation lines between cell groups Prasiola furfuracea
Long narrow thallus with frilled and wavy edge, tapering in both ends, older individuals partly hollow Ulva (‘Enteromorpha’) linza
Thallus distromatic, 1 pyrenoid per cell Ulva fenestrata
(Ulva lacinulata probably under-reported, broad and undulated, margin with “teeth”)
Intertidal and with a very torn edge of thallus, spring, up to 6 pyrenoids in elongated long cells towards base Monostroma grevillei
Edge of blade not torn or only torn in outer parts, one pyrenoid per cell 8
Blade with elongated cells towards base, blade torn in outer parts and with rounded sporangia in groups Protomonostroma undulatum
In basal parts vegetative cells have elongated rhizoids, blade not torn and disintegrating in outer parts Gayralia oxysperma
Key for tube formed taxa (Blidingia, Capsosiphon, some Ulva (‘Enteromorpha’)). Some important characters in bold
| Species | Habitat | Habit | Cell arrangement | Pyren-oids |
|---|---|---|---|---|
| Capsosiphon fulvescens | On rock in high intertidal, often in polluted sites | To 20 cm, narrow, sometimes branched | Characteristic pattern of 2 or 4 small cells (to 10-12 μm) together in groups, separated by thick cell walls |
1 per cell |
| Blidingia minima | High intertidal | To 10 cm long and 4 mm wide, often smaller. Several ind. from same attachm. disc. | Small cells (5-10 μm), may be arranged in rows in the narrowest parts. | 1 per cell |
| Blidingia marginata | Brackish water | Like B. minima, but more rare | Small cells, always arranged in rows | 1 per cell |
| Ulva linza | Semi-exposed in rock pools or shallow | Light green, flat with wavy edge, hollow margins | Cells (15-20 μm) arranged in rows, rectangular with rounded corners | Normally 1 per cell |
| U. intestinalis | Most common Ulva, very common in rock pools | Tubular and narrowing to the base. Can be compressed. | Characteristic hood-shaped chloroplast, placed apically in cell. Cells 8-20 µm diam. |
1 per cell |
| U. compressa | Variable, but not in low salinity | Variable, but much branched and often compressed | Characteristic hood-shaped chloroplast, usually placed apically in cell. Cells 15-30 µm | 1 per cell |
| U. prolifera | Abundant at eutrophicated sites | Very variable, may be branched or not | Cells to 18 μm in longest direction and can be placed in long rows | 1 per cell centrally placed |
| U. flexuosa | Variable | Normally only first order branches | Large cells (to 30 μm in longest direction) rectangular and arranged in rows | (1)-2-(3) per cell |
| U. clathrata | Variable | Highly branched tubes | Large cells (20-50 μm in longest direction), often in rows. Chloroplasts creating a lattice-like pattern |
Several per cell |
| U. criniata | Closely related to U. clathrata | Highly branched, with some short thorn-like branches | Large cells (20-50 μm in longest direction), often in rows. Chloroplasts creating a lattice-like pattern | Several per cell |
Thallus siphonous with main axes, side branches more or less in one plane, normally no cell walls 14
Thallus siphonous and small, irregularly branched, cell wall formes between main axis and side branch Derbesia marina
Side branches not regularly in one plane Bryopsis hypnoides
Branches regularly in one plane Bryopsis plumosa
Thallus lacks hook-formed branches and/or rhizoids (with little pigment) growing downwards along axes at the base, and have side branches always initiated from top part of a cell 16
Thallus with short hook-formed branches and/or rhizoids (with little pigment) growing downwards along axes at the base 17
Key for marine (and marine-brackish) Lychaete and Cladophora. Some important characters underlined:
| Species | Habit | Branch system | Cell shape and size | Habitat |
|---|---|---|---|---|
| Lychaete pygmaea | Diminutive; to 1.5 mm | Irregular | Barrel-shaped, discoid holdfast | Sublittoral |
| Cladophora rupestris | Stiff, broom-like tufts, dark green | Irregular, 1-4 laterals per cell | Main axes cell diam. 90-220 µm, length:width ratio 2-7. Thick cell wall | Intertidal, common |
| C. albida | Dense tufts with spongy texture | Main axes with branches of different age, often bundles of flexed branches | Main axes cell diam. 20-90 µm, l:w ratio 1.5-8. Apical cell rounded tip | Intertidal, often in rock pools |
| C. dalmatica | Light pale to grass green. | Main axes ending in acropetal to irregular branching. Tips often bent (falcate) | Apical cell diam. 13-55 µm. Main axes cell diam. 60-150 µm, l:w ratio 2-20. Cell walls thin, apical cell rounded tip | Marine-brackish, rock pools to shallow subtidal |
| C. flexuosa | Genetically close to C. sericea and C. albida | |||
| C. hutchinsiae | Coarse tufts to 40 cm | Younger branches between older ones (sometimes branches slightly acropetal in tips) | Ap. cell diam. 90-195 µm. Main axes cell diam. 200-400 µm, l:w ratio 1-3.5 | Littoral and upper sublittoral, rare in Norway |
| C. laetevirens | Spongy tufts | Branches often end with acropetal, sometimes flexed or falcate branching | Ap. cell diam. 35-110 µm. Main axes cell diam. 100-260 µm, l:w ratio 2-10 | Littoral and upper sublittoral, rare in Norway |
| C. sericea | Light green, branching angle often < 45° | Younger branches between older ones | Main axes cell diam. 55-170 µm, l:w ratio 1-15. Apical cell tapering | Marine to brackish, in the littoral zone |
| C. vadorum | Akinets may occur: cells short and thick walled | Branching with acropetal organization in attached individs | Main axes cell diam. 120-200, l:w 2-11 | Brackish localities |
| C. vagabunda | Light to dark green | Main axes ending in acropetal branching | Main axes cell diam. 80-300 µm, l:w ratio 1.5-15 | Marine – brackish, often loose lying in sheltered bays |
Big, dark green thallus, some short pointed or spinous branches, grows in wave-exposed intertidal during spring Acrosiphonia arcta
Small, light green thallus, densly branched and with a spherical outline, wave-exposed intertidal during spring Spongomorpha aeruginosa
Thin entangled thalli, < 100 µm in diameter, need microscope to see each individual 19
Macroscopic, uniseriate thallus, > 200 µm in diameter 23
Thallus with a few 1-4 celled branches Rhizoclonium riparium
Thallus without a few short branches 20
Forming a green felt-like cover on rock in spring 22
Forms soft, light green ”bundles” of curly thalli entangled with other algae, cells 50-100 μm in diam Chaetomorpha ligustica.
Thallus with band-shaped, parietal chloroplast, in wave-exposed intertidal during spring Ulothrix sp.
Thallus not with such chloroplast, cells slightly barrel-shaped, often in association with Ulothrix Urospora sp.
Thallus dark green and with big cells (basal cell 1-3 mm long), grows wave-exposed in shallow subtidal Chaetomorpha melagonium
Thallus bright green, dense vegetation in rock pools during summer, or entangled in high intertidal, cells 200-300 μm in diameter Chaetomorpha aerea
