An odd name for a flower perhaps but an appropriate one. Zigzag clover (Trifolium medium) gets its name from the stem which goes one way to a leaf joint, then turns and heads off in another direction to the next leaf joint and so on, the stem grows in a zigzag.
The flower head itself is not unlike red clover but that said it is quite easily distinguishable. The zigzag-clover is a darker pink and the individual florets are more open and spreading without white marks; it is quite obvious when you see it. Unlike red clover which has a reddish stem, zigzag has a pale green stem and pale green leaves, the higher leaves being a little darker than those below. It often grows in large 'clusters' whilst red clover often covers a large area but each plant is separate.
Once quite common in pastures in the British Isles it is now far less so due to habitat loss. It likes heavy clay soils and so it is not particularly common in Dorset.