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 |
|---|---|---|
| Mallomonas sp. | 1 | unicellular chrysophyte: flagellate with silica scales |
| Mallomonas caudata | 1 | |
| Mallomonas heterospina | 1 | |
| Massartia | 1 | unicellular dinoflagellate |
| Mastogloia elliptica | 1 | Diatom, sometimes in colonies within a mucilage coat |
| Melosira varians | 1 2 | filamentous Diatom: similar to Aulacoseira, has cylindrical cells linked by spines. |
| Merismopedia | 1 2 3 4 5 6 | colonial Cyanobacterium (coenobium): spherical blue-green cells in multiples of 4 arranged in flat sheets in a square formation |
| Merismopedia elegans | 1 | |
| Merismopedia tenuissima | 1 | |
| ?Mesotaenium sp. | 1 2 3 4(dividing) | 'Saccoderm' desmid; has a single chloroplast: this example has 4 longitudinal ridges which is not reported in FAFBI. The cells were found in dense mucilage adhering to moss on a greenhouse roof. |
| Micrasterias | Link to illustrated list | unicellular Desmid: semicells are divided by several deep incisions. |
| Micrasterias americana | 1 2 | |
| Micrasterias crux-melitensis | 1 2 | |
| Micrasterias fimbriata | 1 2 3 4 5 | |
| Micrasterias jenneri | 1 2 | |
| Micrasterias papillifera | 1 2 3 | |
| Micrasterias pinnatifida | 1 | |
| Micrasterias radiosa | 1 2 3 4 5 6 | |
| Micrasterias rotata | 1 2 | |
| Micrasterias thomasiana v. notata | 1 2 3 4 | |
| Micrasterias truncata | 1 | |
| Microcrocis geminata | 1 | colonial Cyanobacterium: cells look similar to Merismopedia, but are clustered randomly. |
| Microcystis | 1 2 3 4 5 | colonial Cyanobacterium: many small cells randomly arranged in colonial mucilage without definite shape. Gas vacuoles may be present, when this alga is forming a bloom. |
| Microcystis aeruginosa | 1 2 3 4 5 | |
| Microcystis flos-aquae | 1 2 3 4 5 6 | |
| Microspora | Descriptive notes | filamentous Chlorophyte: unbranched, with a net-like chloroplast and barrel-shaped cells. The cell wall is made up of H-pieces, which can be seen at the ends of filaments (but do not confuse with broken cells eg. in Ulothrix), or the joins may be seen mid-way along a cell. |
| Microspora spp. | 1 | |
| Microspora 8µm. | 1 | |
| Microspora 11µm. | 1 2 | |
| Microspora 16µm. | 1 | |
| Microspora 17µm. | 1 2 3 | |
| Microspora 20µm. | 1 2 3 4 5 6 7 | |
| Microthamnion | 1 2 3 | filamentous Chlorophyte: quite a small plant, frequently branching with parietal plate choroplasts |
| Mischococcus confervicola | 1 2 3 | colonial Chlorophyte: spherical cells in linear groups of 4 at the ends of branching threads |
| Monoraphidium arcuatum | ?1 2 | |
| Monoraphidium contortum | ?1 | unicellular Chlorophyte, slender cells pointed at both ends |
| Monoraphidium komarkovae | ?1 | |
| Monostroma | 1 | colonial chlorophyte forming a single-layered flat plate of cells |
| Mougeotia | Descriptive notes | filamentous
Chlorophyte: unbranched* with cylindrical cells containing an axile
ribbon-like chloroplast which can orient itself relative to the light;
frequently seen twisted in different planes. Pyrenoids readily
visible. *short rhizoid-like branches of 1-2 cells may sometimes form. *species can not be distinguished without details of reproduction being known: see table for possibilities based on dimensions |
| Mougeotia 5µm. | 1 2 | |
| Mougeotia 8µm. | 1 2 3** 4 5 6 7 8 9 | ** examples of aberrant chloroplast morphologies |
| Mougeotia 11µm. | 1 2 3 4 | |
| Mougeotia 12µm. | 1 | |
| Mougeotia 14µm. | 1 2 3 4 5 | |
| Mougeotia 16µm. | 1 2 | |
| Mougeotia 20µm. | ||
| Mougeotia 22µm. | 1 2 | |
| Mougeotia 25µm. | 1 2 3 | |
| Mougeotia 28µm. | 1 | |
| Mougeotia 32µm. | 1 2 3 4 5 6 7 8 9 10 11 12 | |
| Mougeotiopsis | 1 2 3 4 5 6 7 8 | filamentous Chlorophyte: unbranched with cylindrical cells containing an axile ribbon-like chloroplast which can orient itself relative to the light; frequently seen twisted in different planes; no pyrenoids |