Notes: The white variety shown here is Achillea millefolium and is naturalised throughout much of the North America. Some consider it to be a circumpolar native species. The yellow variety shown here is Achillea filipendulina, which is commonly sold in regular nurseries. It is a fine looking Yarrow, but it is not native to North America and has little atttraction for insects. This species is less likely to spread and is easier to manage. Many cultivars and hybrids in a variety of pastel colours are widely available, but they do not seem to be anywhere near as attractive to insects. Achillea millefolium, the weed that grows on the roadsides, can be aggressive, but attracts more insects. None of these plants are recommended in a wildlife garden and there are better wildlife plants out there that are easier to manage. Alexanders are excellent alternatives for Yarrows as they are native and have greater ecological function.