Epipactis helleborine var. castanearum is a plant smaller and more slender than Epipactis helleborine var. helleborine with a thinner stem, smaller leaves and fewer flowers.

This taxon was recently described and it differs from the type-species especially by its ecology, it grows on acidic substrate, particularly among Chestnut trees or Holm oak in Ardèche and Hérault.

This variety blooms quite early in May.