This group includes several genera, and species are difficult to identify. Two species are relatively easy to identify:
Pseudoralfsia verrucosa: brown crusts with a rounded outline and light edge, common in rock pools.
“Aglaozonia”: relatively loosly attached to the substratum, rounded lobes at the edge.
The sporophytic stage of Cutleria multifida
Thallus either like a button (flat disc) or with an irregularly spherical outline 4
Thallus different 6
Vegetative thallus like a button (flat disc), intertidal, long dichotomously divided receptacles when fertile Himanthalia elongata
Thallus with a irregularly spherical outline 5
Thallus becomes hollow, parenchymatic tissue, surface covered with small cortex cells Colpomenia peregrina
Thallus with pseudoparenchymatic tissue (rows of cells sliding away from each other under pressure), surface covered with 2-5 celled paraphyses Leathesia marina
Uniseriate and branched, but axes so strongly intertwined that they appear as compact axes (“dreadlocks”). Short, hook-formed branches Spongonema tomentosum
Thallus different 7
Thallus small (often < 5 cm), having narrow and compact axes, often flattened with an indistinct mid-rib, irregularly branched. Individuals grow intertwined in turf high in the intertidal at special localities, rare Fucus cottonii
Thallus different 8
Thallus like unbranched axis, sometimes with hairs (which may be pigmented) or very short side branches 9
Thallus different 14
Erect part of thallus like uniseriate small (max 2 cm) axes, growing together in brush-like tufts epiphytically on Fucus Elachista fucicola
Mature thallus pluriseriate 11
Thallus covered with short side branches and hairs Myriotrichia clavaeformis
Thallus not with short side branches 12
Thallus pluriseriate and with hairs Litosiphon laminariae
Thallus pluriseriate and lacking hairs Pogotrichum filiforme
Long thallus > 1 m in summer, colourless hairs, old individuals hollow Chorda filum
Short pigmented assimilation hairs starting some distance from the base, only in spring in South Norway Halosiphon tomentosus
Hollow in most parts, branching from main axes (often oppositely branched) Striaria attenuata
Thallus not branched 16
Intertidal, mature individuals with regular constrictions, several thalli originating from a common attachment point, spring (small individuals may appear compact) 17
Mature thallus hollow and inflated but not with regular constrictions 18
Up to 50 cm tall, plurilocular gametangia (uniseriate) when fertile but lack paraphyses, outer cortex layer 2-3 cells, medulla 4 cells thick Scytosiphon lomentaria
Up to 35 cm tall, plurilocular gametangia and unicellular paraphyses when fertile,
outer cortex layer 2 cells, medulla 2-3 cells thick Scytosiphon promiscuus
(In addition an unknown Scytosiphon taxon has been recorded on the southwest coast of Norway. For proper identification of species sequencing is advised)
Thallus hollow but dorsiventrally flattened Asperococcus ensiformis
Thallus not dorsiventrally flattened 19
Thallus elongated and up to 30 cm long, inflated and bulbous, summer Asperococcus bullosus
Smaller, thalli like narrow tubes, often epiphytic Asperocuccus fistulosus
Thallus flat and branched or with a blade-formed part 21
Thallus with round or rounded axis in cross section and branched 44
Thallus like an unbranched blade or with a stipe carrying a blade-formed part which may be divided (like fingers on a hand) 22
Thallus with flat or flattened branches 33
Thallus big and having a conspicuous stipe and blade, the blade can be plain flat, divided like fingers on a hand or have a mid-rib 23
Thallus smaller (< 20 cm) and with a small or inconspicious stipe 29
Thallus with a round (or rounded) stipe, attached by branched hapteron 25
Lamina with hair groups, thallus with a broad, flat, twisted or frilled stipe and unbranched, knobby (in large individuals) holdfas Saccorhiza polyschides
Thallus with stiff and long stipe, subtidally and wave-exposed Laminaria hyperborea
Thallus with a flexible stipe, forming a zone in the upper subtidal, wave-exposed Laminaria digitata
Lamina with very frilled or wavy edge and often undulated middle parts Saccharina latissima
Lamina plain and flat without frills or undulations 28
Plain lamina with hair groups, North Norway only Saccorhiza dermatodea
Big and non-sectioned flat lamina: forms of [speceis]Laminaria hyperborea[/species] and L. digitata which develop at sites with little water movement from waves and currents
Attached by a small disc 30
Attached by a small hapteron: juv. Laminaria sp. or Saccharina latissima
A small “ring” at the bottom of the stipe, hair groups on lamina: juvenile Saccorhiza polyschides
Not a small “ring” at the bottom of the stipe, very short stipe 31
Thallus leaf-formed and narrow, growing in bundles, cross section shows small cortex cells and elongated inner cells, intertidal and wave-exposed 32
Thallus leaf-formed and narrow, cross section shows cells with more or less same size and form Punctaria*
* Punctaria plantaginea common during spring, blade 4-6 cells in cross section
Blade > 2 mm and up to 5 cm wide, growing in small bundles intertidally during spring, wave-exposed Petalonia fascia
Blade very narrow (< 2 mm), growing in small bundles intertidally during spring, wave-exposed Planosiphon zosterifolius
Thallus not dichotomously branched 35
Thallus dichotomously branched, but may have additional side branches 36
Thallus flat and oppositely branched, side branches narrowing towards base Desmarestia ligulata
Thallus irregularly divided in narrow parts, each ending in a small hair tuft Cutleria multifida
Thallus dichotomously branched and with additional side branches, axes flat and strap-like with relatively large gas vesicles Ascophyllum nodosum
Thallus dichotomously branched only 37
With half-piped formed branches, growing in uppermost part of the intertidal, sheltered Pelvetia canaliculata
Thallus with thin, flat branches, growing submerged Dictyota dichotoma
Brackish species, often in river outlets, thallus relatively thin and flexible and often with inflated areas, and often the same individual can have varying width of branches Fucus ceranoides
Stiffer thallus, not growing exclusively in brackish sites 41
Thallus with an indistinct mid-rib and having caecostomata 42
Thallus with a clearly visible mid-rib 43
Thallus to 10 cm, growing only in strongly wave-exposed intertidal, long swollen receptacles Fucus distichus
Larger thallus, often growing in harbour areas, long and swollen receptacles Fucus distichus subsp. evanescens
Thallus stiff and flat, elongated receptacles, dioecious, semi-exposed intertidal Fucus vesiculosus f. linearis
Thallus often twisted, during summer with round receptacles hermaphroditic, upper intertidal, sheltered Fucus spiralis
Thallus branched and with round or rounded axis in cross section:
Thallus fully or mainly uniseriate 45
Tallus pluriseriate in all parts (except apical cells or short side branches) 57
Erect part of thallus unbranched, brush-like tufts epiphytically on Fucus Elachista fucicola
Thallus branched in all parts 46
Thallus pluriseriate in basal parts or with some cells longitudinally divided 47
Thallus uniseriate in all parts 51
Thallus with mainly opposite branching from main axes 48
Thallus not oppositely branched, or only occasionally 49
Thallus pluriseriate in basal parts, oppositely branched or branches in whorls, or with unilocular sporangium opposite of branch, often epiphyte on Cladophora rupestris Isthmoplea sphaerophora
Thallus may be pluriseriate in basal parts, is mainly oppositely branched from main axes, with conspicuous reproducing cells (1-2) placed intercalary in side branches Tilopteris mertensii
Thallus may have round monosporangia with a dark brown content, normally on short branches Haplospora globosa
Thallus with intercalary sporangia and gametangia, forming cell rows 50
Intercalary sporangia or gametangia, disc-formed chloroplasts, may have some opposite branches and some cells longitudinally divided Pylaiella littoralis
Loose-lying, short side branches and terminal sporangia common, rare Pylaiella varia
With occasional opposite branching, Intercalary sporangia or gametangia,
forming cell rows, disc-formed chloroplasts 52
Sporangia and gametangia as side branches, elongated or cone-shaped 53
Intercalary sporangia (unilocular or plurilocular), disc-formed chloroplasts, may have some opposite branches and some cells longitudinally divided Pylaiella littoralis
Loose-lying, short side branches and terminal sporangia common, rare Pylaiella varia
Densely twisted axes (“dreadlocks”) and with small hook-formed side branches, often epiphyte on Fucus Spongonema tomentosum.
Not with small hook-formed side branches 54
Stunted sporangia without stalk, often in series, disc-shaped chloroplasts 55
Strongly elongated plurilocular sporangia often with a short stalk, chloroplast ribbon-shaped 56
Key for the genus Hincksia:
| Species | Size | Branching | Sporangia | Comment |
|---|---|---|---|---|
| H. hincksiae | To 10 cm | Branches often to one side in upper part | Adaxially in series, so dense that the sides meet | Often epiphyte on Sacchoriza polyschides |
| H. sandriana | To 10 cm | Branches in series to one side | Adaxially in series, not so dense that the sides meet | May also have unilocular sporangia |
| H. granulosa | To 15 cm | Branching often opposite | Sporangia round or rounded, often somewhat curved | |
| H. ovata | To 4 cm | Opposite or sparsely | Sporangia often on a one-celled stalk |
Brances in bundles especially in upper part, plurilocular sporangia often in rows adaxally on branches, not ending in a pseudohair Ectocarpus fasciculatus
Plurilocular sporangia elongated and often terminating in a long pseudohair Ectocarpus siliculosus
Main branching irregular, in addition axes are densely set in all directions with short branches of determined growth 58
Main axes are not densely set with whorls of short side branches 59
Short, uniseriate side branches densely set and whorls not present, thallus is normally attached, often in rock pools Cladostephus spongiosus
Short side branches in whorls (verticillate) and separated by internodes (except in tips), normally loose-laying Cladostephus hirsutus
Below top cells the axes are pluriseriate, and clearly divided in segments of cells with longitudinal divisions (seen in microscope, young shots). Axes may be covered with rhizoidal cortex 60
Axes not clearly divided in such segments in any parts 61
Key for Halopteris, Sphacelaria, Chaetopteris, Battersia, Sphaceloderma, Protohalopteis in Norway:
| Species | Branching | Rhizoidal cortex | Cross div. of cells in segments | Propagule and zoidangia | Dimentions | Comment |
|---|---|---|---|---|---|---|
| Halopteris scoparia | Alternating from main axes, last order branch very pointy | No | – | – | To 4-5 cm (in Norw.) | Attached form rare, loose-laying form in sheltered bays |
| Sphacelaria plumula | Feather branching | No | No | Propagule w. 3 short horns (branches) | To 2 cm | |
| S. cirrosa | From main axes | No | No | Propagule w. 3 horns and 1 hair | To 3 cm, axes to 100 μ wide | Often epiphytic (mainly Halidrys siliquosa) |
| S. rigidula | Irregular, thalli in small bushes | No | (no) | Propagule with 2-4 horns. Uni-locular zoidangia on a curved cell | To some cm | Stolon growth. Branches of propagule not constricted at base |
| S. triluboides | Absent or sparsely | No | Rare | Propagule w. 2 short horns | Erect axes to 55 μ wide | Solitary hairs frequent. Rare species |
| Chaetopteris plumosa | Apical feather branching | Yes from cells of segment in all planes | – | – | To 10 cm | Basal parts dark and coarsely branched. Common |
| Battersia plumigera | Apical feather branching | Yes from cells in the same plane as side br. | – | Presence in Norway uncertain | ||
| B. arctica | Irregularly feather br. | On main axes, sparsely | Yes | Rare in Norway | ||
| B. racemosa | Irregular, sparsely | No | Yes | Zoidangia in groups, no propagule | To 2 cm, axes to 55 μ wide | Grows in sandy rock pools |
| Sphacelo-derma caespitulum | Sparsely | No | Yes | Pluriloc on 3-5 celled stalk, no propagule | To 1 cm, axes to 35 μ wide | Small erect axes from a thick basal crust |
| Sphacelorbus nanus | Sparsely | No | yes | Uniloc. on a short stalk, pluriloc. on separate plants. No propagule | < 1 cm, filaments to 23 (30) μ wide | Rare in Norway, Stolon growth, forms mats |
| Protohalop-teris radicans | Irregular, sparesly | No | Yes | Uniloc. often sessile, pluriloc. on separate plants. No propagule | To 2 cm, filaments (upright) to 60 μ wide | Stolon growth, forms dense mats |
Thallus with gas vesicles (round or elongated like pea pods and ending in a narrow tip) on short stalks 62
Thallus without gas vesicles (or with very few) 63
Thallus with small leaves and small, round gas vesicles Sargassum muticum
Gas vesicles are elongated with compartments (“pea pods”), main axes are flattened Halidrys siliquosa
Thallus with a consistent regular branching pattern or partly so 64
Thallus with irregular branching 66
With long, dichotomously branched receptacles attached to a button-formed vegetative part Himanthalia elongata
With opposite or whorl branching 65
Consistently oppositely branched Desmarestia viridis
Commonly with opposite or whorl branches, hollow in most parts Striaria attenuata
Surface covered with paraphyses or assimilation filaments (seen in microscope) 67
Surface with angular cortex cells 71
Thallus to 5 cm, with short branches and epiphytic on Zostera Cladosiphon zosterae
Thallus larger and with relatively long branches 69
Thallus with relatively long 1st order branches and short 2nd order branches, branches of equal thickness: Eudesme virescens or Eudesme borealis (very similar, in E. borealis axes may be thicker in lower parts and tapering upwards)
Thallus with branches of unequal thickness, assimilation filaments with barrel shaped cells at basis Mesogloia vermiculata
Alternately branched from one main axis, almost only branches of 1rst order, thallus not hollow, low intertidal during summer Chordaria flagelliformis
Long 1rst order branches and short 2nd order branches ending in a hair, axes hollow in lower parts, unilocular sporangia Acrothrix gracilis
Fertile structures in conspicuous sori on surface of axes, consisting of sporangia, paraphyses and hairs 72
Thallus not with such sori 73
Pale yellowish, uneven and knotty surface with darker spots (sori), loose-laying in sheltered areas during summer, irregularly branched and axes with one central cell row Spermatochnus paradoxus
Similar to S. paradoxus, but with 4-5 central cell rows, growing epiphytically on Fucus during summer Stilophora tenella
Thallus irregularely branched, with round to flattened axes (2-3 mm thick), laying loose in intertidal in sheltered bays. Ascophyllum nodosum f. scorpioides, see photos under Ascophyllum nodosum
Thallus with thinner axes and sublittoral 74
Irregular branching, dark and coarse branches set with small “spikes” during winter, new growth in spring seen as light brown shoots set with small bundles of hairs Desmarestia aculeata
Thallus not with small “spikes” 75
Growing shoots ending in a hair, axes with rectangular cortex cells covering large inner cells (microscope) 76
Growing shoots not ending in a hair, rounded cortex cells, often epiphytic on Chordaria flagelliformis Dictyosiphon foeniculaceus
Rectangular cortex cells covering elongated inner cells (not always easy to see) Stictyosiphon tortilis.
Rectangular cortex cells covering large, round inner cells (easy to see), small branches often uniseriate Stictyosiphon soriferus
