IDs have been checked against "The Freshwater Algal Flora of the British Isles" (FAFBI. Some older IDs done using "How to Know the Freshwater Algae" (Prescott).
Question marks (?) added where ID is uncertain.
| Name | Image Links | Description |
|---|---|---|
| Caloneis, C. amphisbaena |
1 | pennate diatom |
| Calothrix | 1 2 3 4 5 | filamentous Cyanobacterium: tapering, usually unbranched sheathed filament with terminal heterocyst. See also Dichothrix |
| Calothrix parietina | 1 2 3 | filamentous Cyanobacterium: tapering, usually unbranched sheathed filament with terminal heterocyst. See also Dichothrix |
| Ceratium furcoides | 1 | Dinoflagellate with short horns |
| Ceratium hirundinella | 1 2 3 4 5 6 | Dinoflagellate with 4 prominent horns |
| Chaetonema irregulare | 1 2 3 | branched filamentous Chlorophyte: has hair cells, often broken short |
| Chaetopeltis | 1 2 3 | colonial Chlorophyte (Tetrasporales) growing as a loose disc on surfaces, some cells with 1-2 unsheathed setae |
| Chaetophora | 1 2 3 4 5 6 | branched filamentous Chlorophyte: colony forms hemispherical clumps on surfaces, enveloped in a dense mucilage sheath. Repeated branching, terminal cells pointed or bearing hairs, chloroplast a parietal band |
| Chaetophora incrassata | 1 2 | branched filamentous Chlorophyte: colony forms hemispherical clumps on surfaces, enveloped in a dense mucilage sheath. Repeated branching, terminal cells pointed or bearing hairs, chloroplast a parietal band |
| Chaetosphaeridium | 1 2 | colonial Chlorophyte: a cluster of globular cells, each with a sheathed seta |
| Chamaesiphon | 1 2 | Cyanobacterium: short, grey filament epiphytic on other algae |
| Characium | 1 2 | Xanthophyte: small oval / spindle-shaped cell attached to a surface by a stipe; green, parietal plate chloroplasts |
| Chlamydomonas | unicellular Chlorophyte (Volvocales) with flagella | |
| Chlorella | 1 2 | unicellular Chlorophyte: cells spherical, cup or plate-like chloroplast |
| ?Chlorella saccharophila | 1 | cells oval |
| Chlorella vulgaris | 1 | cells oval |
| ?Chlorosarcina | 1 | colonial Chlorophyte: small number of cells packed in a mucilage sheath, cells angular from mutual compression: eye-spot present(?) |
| ? Chlorosarcinopsis | 1 2 3 | colonial Chlorophyte: cells in multiples of 4, not enclosed in a mucilage sheath, cell walls flattened by mutual compression |
| Chroococcus dispersus | 1 | colonial Cyanobacterium, hemispherical cells in pairs within colonial mucilage |
| Chroococcus limneticus | 1 2 3 4 5 6 7 | |
| Chroococcus turgidus | 1 2 3 4 | |
| Chroococcus varius | 1 | |
| Chroodactylon (Asterocy(s)tis) | 1 2 3 4 5 6 | filamentous Rhodophyte: false-branched filaments with stellate chloroplasts and pyrenoid: frequently blue-green |
| Cladophora | 1 2 3 4 5 | branched filamentous Chlorophyte; coarse texture; cells large, net-like chloroplasts, thick cell walls. |
| Closteriopsis acicularis | 1 2 3 | unicellular Chlorophyte: long and needle-like; compare with Monoraphidium - Closteriopsis shows the presence of pyrenoids while Monoraphidium does not |
| Closterium | 1 (link to illustrated list) |
unicellular Desmid, varying from crescent shaped to straight: radius of curvature, dimensions and wall ornamentation distinguish species |
| Closterium ?abruptum | 1 | |
| Closterium acerosum | 1 2 | |
| Closterium aciculare | 1 2 3 4 | |
| Closterium angustatum | 1 2 3 | |
| Closterium attenuatum | 1 2 3 | |
| Closterium baillyanum | 1 2 | |
| Closterium closterioides | 1 2 | |
| Closterium cornu | 1 2 3 4 | |
| Closterium costatum | 1 2 3 4 5 | |
| Closterium dianae | 1 2 3 4 5 | |
| Closterium dianae v. minus | 1 2 3 | |
| Closterium dianae v. pseudodianae | 1 2 3 4 | |
| Closterium directum | 1 2 3 | |
| Closterium ehrenbergi | 1 2 3 4 | |
| Closterium gracile | 1 2 3 4 | |
| Closterium gracillimum | 1 | |
| Closterium idiosporum | 1 2 3 | |
| Closterium incurvum | 1 | |
| Closterium intermedium | 1 2 3 4 | |
| Closterium jenneri | 1 | |
| Closterium juncidum | 1 2 3 4 | |
| ?Closterium juncidum v. elongatum | 1 2 | |
| Closterium kutzingii | 1 2 3 4 5 6 7 | |
| Closterium lebleinii | 1 2 | |
| Closterium littorale | 1 | |
| Closterium lunula | 1 2 3 4 5 | |
| Closterium moniliferum | 1 2 3 4 5 6 7 8 9 | |
| Closterium navicula | 1 2 3 4 | |
| Closterium ? parvulum | 1 2 3 | |
| Closterium praelongum | 1 | |
| Closterium ralfsii | 1 2 3 | |
| Closterium setaceum | 1 2 | |
| Closterium striolatum | 1 2 3 | |
| Closterium venus | 1 | |
| Coccomyxa confluens | 1 2 3 4 5 | Chlorophyte: cells approx. 3 x 5µm, in pairs within a lamellated sheath |
| Cocconeis pediculus | Diatom: usually found attached to surfaces such as aquatic plants or other algae | |
| Coelastrum | 1 2 3 4 5 ?6 | colonial (coenobium) Chlorophyte: hollow ball of cells joined by processes of the cell sheaths |
| Coelastrum astroideum | 1 | |
| Coelastrum pseudomicroporum | 1 | |
| ?Coelastrum sphaericum | 1 2 3 4 5 6 7 | |
| Coelosphaerium | 1 2 3 4 5 | colonial Cyanobacterium: spherical colony with cells clustered in a layer at the outside, not at the ends of stalks but may have their own sheath (cf. Woronichinia and Snowella) |
| Coelosphaerium kuetzingianum | 1 2 | |
| Coenochloris fottii | 1 2 3 4 5 6 7 8 9 10 11 12 | colonial Chlorophyte (coenobium): spherical cells regularly arranged in a colonial mucilage sheath, without pseudocilia; reproduce by autospores which may remain in mother cell wall for a time: this description is the same as Sphaerocystis; there is doubt about whether these genera are different. |
| Coenococcus planctonicus | 1 3 5 6 7 | "microscopic colonies of 4-8-16-32-(64) celled groups in dense tetrads in an ellipsoid, spherical or irregularly shaped mucilage envelope with clearly delimited outline; cells 5.5-8-(10)µm smooth-walled, chloroplast cup to goblet shaped with single large pyrenoid, reproduces by autospores, 2-4-8 in each sporangium." (FAFBI) |
| Coenococcus polycocccus? | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 | cells sometimes in wreath-shaped groups of 8-32 in a spherical mucilage envelope |
| Coleochaete | Descriptive notes | colonial Chlorophyte: forming either a disc, a hemisphere or a short, sparsely branched filament, some cells with sheathed setae. |
| Coleochaete irregularis a | 1 | branched filament |
| Coleochaete irregularis b | 1 2 | branched filament. Diffuse outline to cells |
| Coleochaete ?orbicularis | 1 2 | pseudoparenchymatous disc, smaller cells than C. scutata |
| Coleochaete pulvinata | 1 2 3 4 5 6 7 8 | hemispherical colony composed of upright, branching filaments |
| Coleochaete scutata | 1 2 | colony composed of branches fused together in a pseudoparenchymatous disc |
| Coleochaete soluta | 1 2 3 4 | disc composed of loosely spreading branches |
| Coleodesmium wrangelii | 1 2 3 | filamentous cyanobacterium: multiple filaments with basal heterocysts within a common sheath. |
| Cosmarium | Link to illustrated list | unicellular Desmid: semicells rounded with simple or decorated margins |
| Cosmarium abbreviatum | 1 2 3 4 | |
| Cosmarium ?bioculatum | 1 2 3 | |
| Cosmarium biretum | 1 | |
| Cosmarium blyttii | 1 2 ?3 4 | |
| Cosmarium botrytis | 1 2 3 4 5 6 7 | |
| Cosmarium botrytis v.mediolaeve | 1 | |
| Cosmarium ? brebissonii | 1 2 3 4 | |
| Cosmarium contractum v. ellipsoideum | 1 | |
| Cosmarium crenatulum | 1 2 3 4 5 6 | |
| Cosmarium crenatum | 1 | |
| Cosmarium ? cyclicum v. arcticum | 1 | |
| Cosmarium depressum | 1 2 3 | |
| Cosmarium depressum v. achondrum | 1 | |
| Cosmarium depressum v. planctonicum | 1 2 3 4 | |
| Cosmarium fontigerum | 1 2 | |
| Cosmarium formulosum | 1 2 3 4 5 6 | |
| Cosmarium granatum | 1 | |
| Cosmarium humile | 1 2 3 4 5 6 | |
| Cosmarium impressulum | 1 2 3 4 | |
| Cosmarium margaritiferum | 1 | |
| Cosmarium ?meneghinii | 1 2 | |
| Cosmarium moniliforme | 1 2 | |
| Cosmarium monomazum | 1 | |
| Cosmarium ovale | 1 | |
| Cosmarium portianum | 1 2 3 4 5 6 | |
| Cosmarium punctatulum | 1 2 3 4 5 | |
| Cosmarium pygmaeum | 1 2 3 4 5 | |
| Cosmarium quadratum | 1 | |
| Cosmarium quadrifarium | 1 | |
| Cosmarium ralfsii | 1 | |
| Cosmarium ralfsii v.montanum | 1 2 | |
| Cosmarium reniforme | 1 2
3 4 5 6 |
|
| Cosmarium reniforme v. compressum | 1 | |
| Cosmarium speciosum | 1 | |
| Cosmarium speciosum v. rostafinskii | 1 2 | |
| Cosmarium subcostatum | 1 2 3 4 | |
| Cosmarium subcrenatum | 1 2 | |
| Cosmarium turpinii | 1 2 | |
| Cosmarium turpinii v. podolicum | 1 | |
| Cosmarium venustum | 1 | |
| Cosmocladium saxonicum | 1 2 3 4 5 6 | colonial desmid in a spherical mucilage sheath; cells similar to Cosmarium, linked by threads of mucilage |
| ?Craticula ambigua | 1 2 | diatom |
| Craticula cuspidata | 1 2 3 | diatom |
| ?Crucigenia | 1 2 | colonial Chlorophyte (coenobium) with oval cells in groups of 4 arranged cruciately, forming a flat plate. Reproduces by autospores, 2 or 4 from each mother cell, oriented at 45° to mother cell |
| Crucigenia fenestrata | 1 2 | colonial Chlorophyte (coenobium) with oval cells in groups of 4 arranged cruciately, forming a flat plate. Reproduces by autospores, 2 or 4 from each mother cell, oriented at 45° to mother cell |
| ?Crucigenia tetrapedia | 1 | colonial Chlorophyte (coenobium) with oval cells in groups of 4 arranged cruciately, forming a flat plate. Reproduces by autospores, 2 or 4 from each mother cell, oriented at 45° to mother cell |
| Crucigeniella | 1 | colonial Chlorophyte (coenobium), differs from Crucigenia in that daughter cells are in same position as mother cell |
| Crucigeniella crucifera | 1 2 | |
| Crucigeniella recta | 1 2 | |
| Crucigeniella rectangularis | 1 2 3 4 | |
| Cryptomonas marssonii | 1 | flagellate |
| Cyanodictyon | 1 | Cyanobacterium: spherical cells in a mucilage tube, often branching |
| Cylindrocapsa | 1 | filamentous Chlorophyte, cell shape varies from cylindrical to elliptical, in a thick, stratified sheath, chloroplast variable; axile, stellate or parietal filling cell. Shows sexual reproduction, forms dark green spherical oogonia. May be bi-or multi-seriate |
| Cylindrocystis | 1 | unicellular Chlorophyte (Saccoderm Desmid): cells short, cylindrical with rounded ends, with 2 stellate chloroplasts |
| Cymatopleura elliptica | 1 2 3 4 | Diatom |
| Cymatopleura solea | 1 2 | Diatom |
| Cymbella aspera | 1 2 | Diatom, curved dorsal margin, ventral margin straight (C.cymbiforme), concave or with a central inflation. Cells motile |
| Cymbella cymbiforme | 1 (valve view) 2 | |
| Cymbella lanceolata | 1 2 3 4 |
