Many divers (including me) casually call underwater lake vegetation “seagrass”. Botanically, that is not correct for Swiss lakes.
Seagrasses are marine flowering plants adapted to seawater and coastal/estuarine habitats, while Swiss lakes are freshwater systems [1]. For lake dives, the better umbrella terms are aquatic plants, submerged aquatic vegetation, or (more technical) macrophytes [2].
The short answer
In Swiss lakes, what you usually see as “underwater meadows” is mostly:
- submerged freshwater vascular plants (for example pondweeds and watermilfoils),
- stoneworts (Characeae), which are macroalgae that can also form dense underwater stands [3][4][5].
Common groups relevant for divers
1) Pondweeds (Potamogetonaceae)
Pondweeds are one of the core freshwater plant groups in Switzerland. Info Flora lists several genera in this family for Swiss flora, including Potamogeton, Groenlandia, and Zannichellia [3].
You may still see older names in books or online. A good example is fennel pondweed: Kew POWO accepts Stuckenia pectinata and lists Potamogeton pectinatus as a synonym [6].
2) Watermilfoils (Myriophyllum)
Info Flora lists multiple Myriophyllum species in Switzerland [4]. One common native species is Myriophyllum spicatum, documented for standing or slow-flowing waters in Switzerland and assessed as Near Threatened (NT) on the national Red List on Info Flora [5].
Info Flora also lists Myriophyllum aquaticum as an aquarium plant originating from South America, rarely escaped/naturalised in Switzerland [7]. That makes it useful to mention when discussing non-native freshwater vegetation.
3) Stoneworts (Characeae)
Stoneworts are frequently overlooked by divers because they can look like “plants”, but they are macroalgae (Charophytes). Info Flora maintains Characeae as a dedicated Swiss flora family page with genera such as Chara, Nitella, Nitellopsis, and Tolypella [8].
In practice underwater, dense stonewort stands may be perceived as “meadows” similar to vascular plant beds.
Why naming matters for dive posts
- It improves biological accuracy for freshwater dive-site descriptions.
- It avoids mixing marine ecology terms into lake contexts.
- It still reads naturally for non-botanical audiences.
For this blog, a practical style is:
- use aquatic plants in general descriptions,
- use aquatic plant meadow when describing broad shallow vegetated zones,
- optionally add scientific names only when needed (for example in species-focused posts).
Practical wording examples
- “Shallow aquatic plant meadow between 3 and 8 meters.”
- “In spring, this plateau has abundant aquatic plants and toad spawn.”
- “Pondweed and stonewort patches are common along the shoreline.”
References
[1] Seagrass-Watch. What is seagrass? (marine/seawater definition).
https://www.seagrasswatch.org/seagrass/
[2] U.S. EPA. Indicators: Macrophytes (definition of aquatic macrophytes).
https://www.epa.gov/national-aquatic-resource-surveys/indicators-macrophytes
[3] Info Flora (Switzerland). Potamogetonaceae (Swiss family page and genera).
https://www.infoflora.ch/en/flora/potamogetonaceae.html
[4] Info Flora (Switzerland). Myriophyllum (Swiss genus page).
https://www.infoflora.ch/en/flora/myriophyllum.html
[5] Info Flora (Switzerland). Myriophyllum spicatum L. (habitat/distribution and status in Switzerland).
https://www.infoflora.ch/en/flora/myriophyllum-spicatum.html
[6] Royal Botanic Gardens, Kew (POWO). Stuckenia pectinata (L.) Börner (accepted name and synonyms incl. Potamogeton pectinatus).
https://powo.science.kew.org/taxon/77099639-1
[7] Info Flora (Switzerland). Myriophyllum aquaticum (Vell.) Verdc. (South American origin; aquarium plant rarely naturalised in CH).
https://www.infoflora.ch/taxonid/1029880
[8] Info Flora (Switzerland). Characeae (Swiss family page with genera).
https://www.infoflora.ch/en/flora/characeae.html