The flowers closely resemble little flies, attracting insects to pollinate them.

They are not easy to spot as their rather drab colouring blends with the surrounding vegetation, but they often form colonies of ten or more plants. The species declined dramatically before 1930, especially in East Anglia. The losses have continued since, but at a reduced rate, mostly due to scrub encroachment, the closing of woodland canopies, woodland clearance and drainage of fens.