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 |
|---|---|---|
| Naegliella | 1 2 3 | colonial Chrysophyte: grows on surfaces as a flat disc of slightly angular cells, in colonial mucilage with tufts of long erect gelatinous hairs. |
| Navicula sp. | 1 | unicellular Diatom: motile, 'boat-shaped', two chloroplasts, one against each side of the girdle; lots of species |
| Navicula capitata | 1 2 3 4 | |
| Navicula capitatoradiata | 1 | |
| Navicula ?cryptotenella | 1 2 | |
| Navicula oblonga | 1 | |
| Navicula protractoides | 1 | |
| Navicula radiosa | 1 2 3 4 5 | |
| Navicula rhynchocephala | 1 | |
| Navicula rhynchocephala v.amphiceros | 1 | |
| Navicula subrhynchocephala | 1 | |
| Neidium iridis | 1 2 | Large Diatom |
| Neidium productum | 1 | unicellular Diatom |
| Nephrocytium | Chlorophyte; cells more or less 'kidney-shaped', in groups of 4 (or multiples) in a mucilaginous sheath | |
| Nephrocytium agardhianum | 1 2 3 4 5 6 | |
| Nephrocytium limneticum | 1 | |
| Netrium | 1 | unicellular Desmid (placoderm): cylindrical with tapering rounded ends, some slightly swollen in the middle, with 2 chloroplasts. (N interruptum has each chloroplast almost divided in 2) |
| Netrium digitus | 1 2 | |
| Netrium interruptum | 1 2 | |
| Nitzschia ?homburgiensis | 1 | unicellular Diatom, 2 chloroplasts located fore and aft in the cell |
| Nitzschia radicula | 1 | |
| Nitzschia sigmoidea | 1 2 3 | unicellular Diatom: some Nitzschia species are sigmoid as in this case |
| Nitzschia scalaris | 1 | |
| Nitzschia scalpelliformis | 1 | Another sigmoid Nitzschia species: this one resembles Gyrosigma, but is distinguished by the chloroplast arrangement |
| Nitzschia vermicularis | 1 | |
| Nostoc sp. | 1 2 3 4 5 | colonial Cyanobacterium: spherical cells form filaments which are crowded together in a firm colonial mucilage |
| Nostoc linckia | 1 2 |
| Name | Image Links | Description |
|---|---|---|
| Oedogonium | Descriptive notes | filamentous Chlorophyte: grows attached to surfaces, unbranched, cells are tapering and/or bulbous, with rings around one end as a result of cell division; chloroplast a network. Feels coarse. Can reproduce sexually as well as vegetatively. |
| Oedogonium 6µm. | 1 2 3 4 5 6 | |
| Oedogonium 15µm. | 1 2 3 4 5 6 7 8 9 10 11 12 13 | |
| Oedogonium 20-30µm. | 1 2 3 4 | |
| Oedogonium 45µm. | 1 2 3 | |
| Oedogonium germling | 1 2 3 | |
| Oedogonium undulatum | 1 2 | one of the few which can be identified to species without seeing the zygote (product of sexual reproduction) |
| Oligochaetophora | 1 2 3 | colonial Chlorophyte: grows on surfaces as a group of a small number of cells each with several long hairs emerging from the colonial mucilage, parietal chloroplast |
| Oocystis | 1 2 3 4 5 6 7 | colonial
Chlorophyte (coenobium): spherical/ oval (sometimes other shapes) cells
in 2, 4, 8...64 series, enclosed in a mucilage sheath, sometimes the mother-cell
wall. Figures 4 and 5 correspond better with Prescott's "Rayssiella" |
| Oocystis borgei | 1 | |
| Oocystis ?elliptica | 1 2 3 | |
| Oocystis lacustris | 1 | |
| Oocystis marssonii | 1 | |
| ?Oonephris obesa | 1 | unicellular or colonial Chlorophyte: one or a small number of cells within mother cell wall remnant; cells ellipsoid or kidney-shaped, one side straight in the case of O.obesa; stellate chloroplast |
| Ophiocytium | 1 2 3 4 5 | colonial Chlorophyte: attached (or some planktonic); cell cylindrical, curved with plate chloroplasts, forming a cluster of single-celled branches at the other end from the holdfast, each may branch again |
| Ophiocytium arbusculum | 1 2 3 | colonial Chlorophyte: attached (or some planktonic); cell cylindrical, curved with plate chloroplasts, forming a cluster of single-celled branches at the other end from the holdfast, each may branch again |
| Oscillatoria 5µm. | 1 2 3 4 5 | filamentous Cyanobacterium: smooth-walled filament composed of short cells, end cell may be a different shape; motile (gliding), grey, brown or blue-green colour; no sheath (cf. Phormidium) |
| Oscillatoria 8µm. | 1 2 | |
| Oscillatoria 11µm. | 1 | |
| Oscillatoria 20µm. | 1 |