British Agency Gears Up to Tackle Invasive, Killer Plant

Boats have been out in force on River Cam, the main river flowing through Cambridge in eastern England, to urgently remove an invasive plant that starves fish and plants of oxygen.

The British Environment Agency had issued an "emergency navigation closure notice" on Nov. 13, closing the section of the river between Bottisham and Upware to eradicate floating pennywort, Cambridge News reported.

Now boats are allowed back on the river, but there are still restrictions in place.

Elliot Furniss, from the Environment Agency Anglia, said people could experience delays of 30 minutes along the stretch.

The waterborne species can grow up to 20 cm a day and the news previously reported concerns that it was damaging fish stocks, birdlife and indigenous plants in River Cam.

One river user even warned that floating pennywort could overrun the waterways in the next 12 months.

The problem species, originally from the USA, arrived in the UK in the 1980s for use in tropical aquariums and garden ponds but was first found in the wild in Essex in 1991.

The plant has fine, hair-like roots and fleshy stems that sink up to 50 cm under water. Its waxy, round kidney-shaped leaves can be up to 7 cm across.