All thistles belong to the daisy family which make up the largest family of flowering plants in the UK after grasses. The flower heads are made up of a number of individual flowers or florets. The leaves and nectar of thistles are a good source of food for insects, and some birds, such as Goldfinch, eat the seeds. So it is always worth taking a good look at thistle plants for other wildlife. On a patch of thistles, I have been watching there are a number of deformed plants where many stems appeared to have fused together into one clump about 6 inches across. I think they are Spear Thistle (Cirsium vulgare). These variations are called Fasciation from the Latin root meaning “band” or “stripe”), it can be caused by a random genetic mutation, a physical injury to the plant and sometimes a parasite.
June flowering starts. The flower buds are developing and getting larger and the joined bud on the top of the fused plant has opened into an elongated flower head.