A weed is a plant growing where it's not wanted. Invasive weeds are an increasing problem in New Zealand with individual species variously affecting agriculture, health, recreational areas and industry. Many of the invasive weeds causing environmental damage start off as ornamental plants in gardens, and become a problem when they 'jump the fence'. In this handbook, garden weeds that are a distinct nuisance to gardeners are examined first, and then the book moves on to target those weeds that threaten our native ecosystems - and yet are quite familiar to most gardeners. Two and sometimes three photographs identify each weedy plant and clear concise headings urge readers to Know it, Understand it, Control it and Replace it. The book divides weeds into herbs, grasses, vines, shrubs and trees with clear technical guidelines regarding the use of herbicides and the disposal of weed waste.