Common knapweed

Look out for common knapweed – one of our later flowering plants. Many of the deep purple compact flowerheads have turned into the black seedheads which remain on their hard branched stems which last throughout winter, while occasional flowerheads stand out at this time of year. Because of the black seedheads it is also known as black knapweed or blackheads. With many insects using the seedheads and others feeding on its leaves and stems – knapweed may be supporting over fifty invertebrates in a complex foodweb, with many of the gall flies, gall midges and small moths feeding on knapweed in turn being preyed on by predatory flies. Common knapweed is part of our native Irish biodiversity.