Chris Mattison / Broad-leaved pondweed (Potamogeton natans) growing among Sphagnum moss in a small pond in Woorgreens Nature Reserve, Gloucestershire, UK

Nick Upton / Broad-leaved pondweed (Potamogeton natans) flowering in a marshland pond, Devon, UK, June

Willem Kolvoort / Longleaf Pondweed (Potamogeton nodosus) River Ijesell, Holland. July.

Wild Wonders of Europe / Lundgren / Current pulling weeds possibly Potamogeton sp, along riverbed, Danube Delta, Romania, June.

Wild Wonders of Europe / Lundgren / Aquatic plant, possibly Potamogeton sp, in river current, Danube Delta, Romania, June.

Adrian Davies / Leaves of Bog Pondweed {Potamageton polygonifolius} New Bridge Marsh, Dartmoor, Devon, England

Niall Benvie / Pondweed {Potamogeton sp} Tansley bog, Beinn Eighe NNR, W Ross, Scotland

Willem Kolvoort / Broad leaved pondweed (Potamogeton sp) underwater in brook, Holland

Willem Kolvoort / Looking up at Shining pondweed (Potamogeton lucens) from bottom of sand winning pit, Holland

Willem Kolvoort / Pondweed (Potamogeton sp) covered with colonies of Bellanimacules (Vorticella), in sand-winning pit, Holland

Heidi & Hans-Juergen Koch / Giant Fire-bellied Toad (Bombina maxima) emerging from pond weed, native to China

Franco Banfi / Northern pike (Esox lucius) amongst Shining pondweed (Potamogeton lucens), Sion, Valais canton, southwestern Switzerland, Europe

Franco Banfi / Northern pike (Esox lucius) amongst Shining pondweed (Potamogeton lucens), Sion, Valais canton, southwestern Switzerland, Europe

Franco Banfi / Northern pike (Esox lucius) amongst Shining pondweed (Potamogeton lucens), Sion, Valais canton, southwestern Switzerland, Europe

Franco Banfi / Northern pike (Esox lucius) amongst Shining pondweed (Potamogeton lucens), Sion, Valais canton, southwestern Switzerland, Europe

Franco Banfi / Pondweed (Potamogeton lucens), Sion, Valais canton, southwestern Switzerland, Europe

Alex Hyde / Broad-leaved pondweed (Potamogeton natans) growing in moorland pool, with raindrops beading on the hydrophobic surface of the leaves. Peak District National Park, Derbyshire, UK. December.

Nick Upton / Broad-leaved pondweed (Potamogeton natans) in heathland pond. Dorset, England, UK. June.

Nick Upton / Common European toad toadlet (Bufo bufo) sitting on a Broad-leaved pondweed (Potamogeton natans) leaf in a pond, Dorset, UK, June.

Nick Upton / Pondweed leafhopper (Erotettix cyane) nymph resting on a leaf of Broad-leaved pondweed (Potamogeton natans), its sole host plant in a heathland pond, Dorset, UK, June. This tiny insect is one of the U...

Nick Upton / Pondweed leafhopper (Erotettix cyane) adult resting on a Broad-leaved pondweed (Potamogeton natans) leaf, its sole food plant, in a heathland pond, Dorset, UK, June. This tiny insect is one of the UK'...

Michel Roggo / Northern pike (Esox lucius) amongst Shining pondweed (Potamogeton lucens) on tbed of Lake Neuchatel, Switzerland, September. Photographed for The Freshwater Project.

Michel Roggo / Northern pike (Esox lucius) amongst Shining pondweed (Potamogeton lucens). Lake Neuchatel, Switzerland, September. Photographed for The Freshwater Project.

Willem Kolvoort / Common toad (Bufo bufo) tadpoles amongst Perfoliate pondweed (Potamogeton perfoliatus) in ditch. Netherlands. May.

Willem Kolvoort / Common toad (Bufo bufo) tadpoles eating algae on Floating pondweed (Potamogeton natans). Netherlands. May.

Will Watson / Reed Beetle (Donacia veriscolorea) on Broad-leaved Pondweed (Potamogeton natans), Shatsky National Natural Park, Volyn Oblast, Ukraine, May.

Will Watson / Fen raft spider (Dolomedes plantarius) and Reed beetle (Donacia veriscolorea) on Broad-leaved Pondweed (Potamogeton natans), River, Volyn Oblast, Ukraine, May.

Michel Roggo / Shining pondweed (Potamogeton lucens), beginning of autumn, Lake Bienne, La Neuveville, Canton of Berne, Switzerland, October. Photographed for The Freshwater Project.

Michel Roggo / Shining pondweed (Potamogeton lucens), Lake Neuchatel, near Boudry, Canton of Neuchatel, Switzerland. August. Photographed for The Freshwater Project.

Michel Roggo / Sago pondweed or Fennel pondweed, (Potamogeton pectinatus) Lake Neuchatel, close to Serrières, Canton of Neuchatel, Switzerland, July. Photographed for The Freshwater Project.

Michel Roggo / Sago pondweed or Fennel pondweed, (Potamogeton pectinatus) Lake Morat, close to Vallamand-Dessous, Canton of Fribourg, Switzerland, June. Photographed for The Freshwater Project.