Areas at Risk of Colonisation in the UK Areas at risk are suitable habitats below about 550 m. The species has been found at a maximum altitude of 443m and can therefore tolerate prolonged cold winter conditions by lying dormant under ice. Cold weather tendds to increase fragmentation increasing rates of spread. Proximity to existing populations will increase the likelyhood of spread to new areas.

Myriophyllum aquaticum (Parrot’s-feather)

Field Recognition Guide

Preferred habitat: shallow (usually <50cm), nutrient rich water at the margins of ponds, lakes, canals and streams.

Key features: two types of leaves, submerged: flaccid highly dissected leaves in a whorl of 4 – 6 around stem, 2 – 5 cm long and emergent: rigid, with 6 – 18 divisions per leaf, 3 – 5 cm long on stems that can reach 30cm above the water surface. White flowers in leaf axils from June.

Reporting: please inform the Non Native Species Secretariat at www.nonnative species.org giving grid reference, extent of infestation, photograph and date of observation, and the Biological records centre at http://www.brc.ac.uk/contact.htm

Further action: Assess the risk of the population you have observed using the risk assessment sheet provided in this pack.