 Ragwort, for instance, was rated as the top flower meadow nectar source in a UK study, and in the top ten in another.Its early blooming period is also particularly helpful for the establishment of bumblebee colonies.Thistles that have been dubbed noxious weeds in the US and elsewhere, such as "Cirsium arvense" and "Cirsium vulgare", have also rated at or near the top of the charts in multiple UK studies for nectar production.