Ceratophyllum demersum (Rigid Hornwort)
| Participant | Municipality (county) | Num. obs. | Num. species | Num. images | Last obs. |
|---|---|---|---|---|---|
| Fauske videregående skole | Nordland, Norway | 2 | 1 | 0 | 1991-09-25 |
| Forskolen for sivile vernepliktige | Møre og Romsdal, Norway | 1 | 1 | 0 | 1992-09-08 |
| Asker videregående skole | Akershus, Norway | 1 | 1 | 0 | 1989-09-21 |
| Nordre Oppdalen Skole | Akershus, Norway | 1 | 1 | 0 | 2004-10-07 |