The Return of the Krabbenscheer: A Dutch Red List Plant Flourishes in Groningen

The Krabbenscheer © Jörg Hempel

The krabbenscheer (stratiotes aloides), a water plant classified as endangered on the Dutch Red List of endangered species, is making a comeback in Groningen, specifically in the Oosterpolder near Noordlaren. This promising news was announced by Het Groninger Landschap, a foundation dedicated to protecting nature in the province.

“One creek is completely filled from begin to end with this aquatic plant,” the organization proudly shared on its official Instagram page. Despite this resurgence, the krabbenscheer remains at risk, with evidence pointing to its disappearance in several areas of the city of Groningen. Research conducted by Bureau Biota and IVN Natuur Educatie highlights the precarious situation. A 2020 report revealed that, of 34 locations where the plant was confirmed in 2019, six had lost the plant’s presence by the following year.

In blue: areas where Krabbenscheer is still present. In red: area where Krabbenscheer disappeared  © Viola Duroni

Threats to Survival

“This plant is particularly endangered in regions with large lakes and peatlands, largely due to changing water conditions,” Kira Tiedge tells The Glass Room, assistant professor at the University of Groningen and a plant science expert. Tiedge adds that many bodies of water are getting overloaded with nutrients, which encourage the spread of invasive species that are harmful to the krabbenscheer.

Despite these challenges, the plant's return in certain areas offers hope for the micro-ecosystem surrounding it. The krabbenscheer plays a crucial role in maintaining biodiversity. “It’s a very stable plant, making it an excellent nesting place for birds,” Tiedge says. Additionally, it provides a vital resting spot for small amphibians such as frogs and salamanders.

One of its most fascinating connections to other species is the plant’s relationship with the green hawker dragonfly (Aeshna viridis), a rare species that depends entirely on the krabbenscheer for reproduction, according to IVN Natuur Educatie. The dragonfly indeed lays its eggs on the plant, drawn to the plant’s unique leaf structure and color. Without the krabbenscheer, the green hawker cannot survive. “It [the krabbenscheer] is also essential for the overall health of the lake or pond,” Tiedge adds, “because stratiotes help control algae, keep the water clear, and are suitable for other living organisms.”

© Viola Duroni

Seasonal Disappearance

Though the the krabbenscheer remains endangered, it is still relatively common in parts of Groningen province, thanks to the region's unique conditions. “It’s cold-tolerant and has the ability to sink to the bottom of the water during winter, where it’s warmer than the surface,” Tiedge explains. As temperatures rise in spring, the plant reemerges, bringing with it stunning white flowers that bloom in warmer weather. This is why people who want to experience the beauty of this plant, unfortunately still have to wait a few months.

The return of the krabbenscheer in certain areas offers a glimpse of hope, but its future remains uncertain, because it remains an endangered species.