Eupatorium
This is a tricky one to summarise as this group of plants is being reduced is size, with many being renamed as Ageratina, Eutrochium and more. The newly names Eutrochium plants we are growing, tend to be in our water garden, as back of the border types. Big heads of many small, pink-purple flowers, very attractive to butterflies, on sturdy, dark or coloured stems. These are clothed with leaves, whorled or opposite. Best grown in a sunny spot, in a good moisture-retentive soil. One Eupatorium we grow is our native species, hemp agrimony, but as a double-flowered form 'Flore Pleno'.
All species of Eupatorium and recently segregated genera (se above) are of great significance to late-summer garden wildlife, although as always doubled forms produce fewer resources that insects are looking for. Honeybees, hoverflies and butterflies, from holly blues to fritillaries just love the flowers, and finches revel in the dense heads of those forms that produce seeds.