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 |
|---|---|---|
| Palmodictyon viride | 1 2 3 4 5 | colonial Chlorophyte: spherical cells in branching tubes of mucilage, with cup-shaped chloroplast |
| Pandorina | 1 2 3 | colonial Chlorophyte (flagellate): spherical / oval colony with cells crowded, pyriform; 2 flagella from each cell projecting through mucilage sheath. Colony motile in a tumbling, rolling motion |
| Paulschulzia tenera | 1 2 3 | colonial Chlorophyte:cells/cell groups in clearly defined spherical mucilage envelope, with individual sheaths and flagellum extending beyond outer envelope |
| Pediastrum sp. | 1 | colonial Chlorophyte: cells angular, crowded together to form a flat disc, cells in outer layer usually ornamented with protuberances, some species have spaces between cells in the middle of the disc |
| Pediastrum angulosum | 1 2 3 4 5 6 7 | |
| Pediastrum boryanum | 1 2 3 4 5 6 7 8 9 10 | |
| Pediastrum boryanum v. cornutum | 1 2 3 4 | |
| Pediastrum boryanum v. longicorne | 1 2 | |
| Pediastrum duplex | 1 | |
| Pediastrum duplex v. rugulosa | 1 2 | |
| Pediastrum tetras | 1 2 3 | |
| Penium exiguum | 1 | unicellular Desmid (Placoderm): cylindrical with rounded ends, cell wall granular, 1 chloroplast in each semicell (sometimes interrupted in P. margaritaceum). |
| Penium margaritaceum | 1 | unicellular Desmid (Placoderm): cylindrical with rounded ends, cell wall granular, 1 chloroplast in each semicell (sometimes interrupted in P. margaritaceum). |
| Phacus | 1 2 3 4 5 | unicellular Euglenophyte: somewhat pear-shaped with an apical process, pellicle marked with striations; motile by means of a flagellum, many chloroplasts |
| Phacus caudatus | 1 | |
| Phacus pleuronectes | 1 2 | |
| Phaeosphaeria | 1 | Chrysophyte ("Golden Algae"); spherical cells with a golden-brown chloroplast in a tubular or net-like colonial mucilage |
| Phormidium 5µm | 1 | filamentous Cyanobacterium: smooth-walled filament composed of short cells, non-motile, grey, brown or blue-green colour; with a thin sheath, forms dense mats or films with a slippery texture |
| Phormidium 9µm | 1 | |
| Phormidium 12µm | 1 | |
| Pinnularia | 1 | unicellular Diatom: Pinnularia spp. have very distinct, feather-like frustule markings |
| Pinnularia maior | 1 2 | |
| Pinnularia nobilis | 1 | |
| Pinnularia ?viridis | 1 | |
| Pleurotaenium coronatum | 1 2 3 | unicellular Desmid (Placoderm): long somewhat cylindrical cell divided into 2 semicells, some spp. with inflated regions near the centre and varied markings on the end faces |
| Pleurotaenium trabecula | 1 2 5 | |
| Pleurotaenium ehrenbergii | 1 | |
| Porphyridium | 1 2 | unicellular Rhodophyte, found on damp soil |
| ?Protoderma | 1 2 | Chlorophyte: filamentous, but forms a flat colony of touching filaments on surfaces. Parietal chloroplast |
| Pseudanabaena | 1 2 | filamentous Cyanobacterium: very small cell diameter (approx. 2µm), beaded appearance as cells slightly separated from each other |
| Pseudokirchneriella subcapitata | 1 2 | Chlorophyte: unicellular or sometimes as coenobia of 4, 8, etc. Cells elongated, spindle- or half-moon shaped (hence the older name); parietal chloroplast. Formerly 'Raphidocelis subcapitata' previously "Selenastrum capricornutum" |
| Pseudoquadrigula | 1 | colonial Chlorophyte (coenobium): cigar-shaped cells lying in groups of 4 within a globular mucilaginous sheath |
| Name | Image Links | Description |
|---|---|---|
| Quadrigula closterioides | 1 2 | colonial Chlorophyte (coenobium): cigar-shaped cells lying in parallel groups of 4 within a globular mucilaginous sheath. (cells in all groups lie parallel, distinguishing it from Pseudoquadrigula) |
| Quadrigula pfizeri | 1 | |
| Quadricoccus verrucosus | 1 2 | colonial Chlorophyte (coenobium):oval cells in groups of 2-4 within a mucilage envelope. Cells are smooth or covered with granules |
| Name | Image Links | Description |
|---|---|---|
| ?Radiococcus nimbatus | 1 2 3 | colonial Chlorophyte, spherical cells in a (usually) spherical mucilage sheath with radiating fibrils |
| 'Raphidocelis subcapitata' | 1 2 | Chlorophyte: unicellular or sometimes as coenobia of 4, 8, etc. Cells elongated, spindle- or half-moon shaped (hence the older name); parietal chloroplast. Formerly "Selenastrum capricornutum", now Pseudokirchneriella subcapitata |
| Rhoicosphenia curvata | 1 2 | heteropolar Diatom: curved, usually attached |
| ?Roya (?obtusa) | 1 2 3 | 'saccoderm' desmid: elongated cylindrical cell with rounded ends, usually slightly bent (this example is rather shorter than usual). The single chloroplast has a notch in the middle |