Common KNAPWEED : Centaurea nigra
Also see THISTLE : index.asp?pageid=731666
You have most likely seen this striking plant and mistaken it for a thistle. But a thistle it is not.
This is a common knapweed, almost a fake thistle. it looks so much like one, but something gives it away. It has no prickles.
Our examples were found along the Leven towpath; their bright purple flowers opening right on cue - in mid-June. The bright pink-purple 'flowers' of common kanpweed are actually composite flower heads made up of many small 'florets' (tiny flowers), surrounded by a crown of long, ragged, pink bracts (leaf-like structures).
Now look at the leafs. They have no prickles like the true thistle, but are elongated and somewhat furry.
Wiki tells us : It is native to Europe but it is known on other continents as an introduced species and often a noxious weed.
Although the plant is often unwanted by landowners because it is considered a weed by many, it provides a great deal of nectar for pollinators. It was rated in the top five for most nectar production (nectar per unit cover per year) in a UK plants survey. It also placed second as a producer of nectar sugar per floral unit, among the meadow perennials, in another study in Britain.
Knapweed looks very much like a thistle.
But look more closely at the leafs.
A hardworking bumble bee attends to a knapweed flower.
The "hundred steps" walk up from Renton to Carman Reservoir is quite a sight in August.
WIKIPEDIA : https://en.wikipedia.org/wiki/Centaurea_nigra