As part of weed management, this spring the City Council is helping target a plant pest called purple loosestrife. It is now an “unwanted organism”, a serious weed that has been sold in the past at nurseries and planted in gardens in Christchurch. It has the potential to become a serious problem around waterways, as has happened in North America. It can colonise water margins, ponds and shallow lakes, and has the potential to clog drainage and irrigation ditches. Each plant can produce millions of seeds, which are mainly dispersed by water.

The Department of Conservation — purpleperil@doc.govt.nz — wants to hear from people about where it is growing in order to work out how best to deal with the pest.

• For more information about this plant and how to identify and destroy it, check the Canterbury Weed Guide on the net, at www.ccc.govt.nz/environment/weeds/