Cephalanthera damasonium.
Cephalanthère à grandes fleurs.
Large white helleborine.
Cephalanthera are generally light undergrowth orchids. The flowers open little. To distinguish the 3 species, it is quite simple: the red cephalanthera has pink flowers, the long-leaved cephalanthera has leaves that start from the base of the plant and form upright swords, the large-flowered cephalanthera has rounder leaves on the entire stem.
You should not always trust the colors of vernacular and even Latin names. The white helleborine has more yellow flowers than the longifolia helleborine and the red helleborine ( rubra ) has pink flowers... As for the size, I found many longifolia helleborines larger than the white helleborines (Large white helleborine in English).
It is therefore essentially on the shape of the leaves that we will distinguish Cephalanthera damasonium presented here from Cephalanthera longifolia .