Ageratina
A large genus of around 290 species from the Americas. Shrubs, mainly Mexico and S. America and herbaceous from N. America. Opposite leaves and flattened clusters of white to pink flowers. Both sometimes scented. Few are grown in the UK, but those that are, the foliage can be the more garden-attractive feature. Some previously known as Eupatorium.
The tiny but numerous flowers that make up the flowerheads contain nectar and pollen that attracts a range of insects including butterflies, flies and bees.