Biology Researcher finds long-lost plant in Lake Constance
Researchers have rediscovered a lost plant species in Lake Constance. The aquatic plant known as fishwort had not been found in Lake Constance since the 1990s.
11.11.2025, 15:13
SDA
The plant was discovered by research diver Almut Hanselmann from the University of Konstanz, as the university announced on Tuesday.
When she dived near Immenstaad (Germany) in January 2025 as part of her regular plant surveys, she noticed that the lake bed was unusually green for this time of year.
Closer examination revealed that the unexpected greening was caused by the plant with the scientific name Groenlandia densa. According to the University of Constance, this plant is hardy and therefore thrives even in the cold season.
Hanselmann's discovery was later confirmed when she documented a strong occurrence of the plant at the same location in June 2025.
Plant in a deep sleep
According to the researchers, the reappearance of the plant is a good sign that the lake is returning to its natural state. They suspect that the water pollution, ammonium and phosphorus contamination of the lake had killed it off.
According to the university, the plant was probably never really gone, but had just been in a kind of "deep sleep" for a long time.
The sediment layers of the lake contain seeds and permanent stages of countless plant species, including those of Groenlandia densa. This material just didn't have the right conditions to spread.
