Sunday, 23 October 2016

Unwelcome Invader at Hemingford Grey (VC31)

Lynne Farrell found Floating Pennywort in the River Great Ouse at Hemingford today. This is a very invasive non-native species that will hopefully be eradicated before it has chance to establish. It would be very unfortunate if it got a foothold and then moved onto colonise the important gravel pit complexes along the river.

Floating Pennywort is a native of North America, but was introduced to Britain by the horticultural trade as an aquatic ornamental. As is too often the case with aquatics, it is a bit of a thug and once it starts to take over its not long before someone thinks it a good idea to turf it out into the nearest watercourse. Spread is somewhat inevitable after that, with this species capable of growing 20cm per day.

This species is well established at Bedford (VC30), so there is a high chance of it being washed downstream into Huntingdonshire. Please keep your eyes peeled, and if you see it report it via the Plant Tracker website or phone app, or by email to

For readers from Yorkshire, it is also depressingly frequent in the Rivers Don, Aire and Calder.

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