Centaurea nigra, Asteraceae
You would probably be able to point out and recognise the blue cornflower, C. cyanus, now endangered in its habitat due to the use of herbicides, but have you ever stopped to look at its much more common relative, black knapweed? The inflorescences of this perennial species native to Europe and widely naturalised in many temperate areas are superficially similar to those of Cirsium arvense, the creeping thistle, and both plants are extremely valuable in sustaining wildlife, from bees and butterflies to granivorous birds like the cardueline finches, which feed on the large seeds. Incidentally I also managed to take my first decent photos of some red tail bumblebees (Bombus lapidarius), I guess a nest was near as I had never seen so many all together.
The root of black knapweed has traditionally been used to treat wounds and sores, particularly those affecting the oral cavity. It isn’t toxic, but only its flowers are edible, and can be used as garnish or to fill in a salad.
Last year I took a short video of a carder bee foraging on this plant, you can click here to have a look!