In a contribution for the Journal of European Orchids (Journal Europäischer Orchideen, vol. 50, 2-4, 2018, p. 221-226), Leslie Lewis presents an overview of the hypochrome forms of Neottia nidus-avis and new findings in England. In the introduction, she explains that these orchids have colour pigments – chlorophyll and carotinoids. However, colour variants are also occasionally found, the author writes.
It might be questionable ob these colour variants should have a taxonomic relevance. But at least there are scientific descriptions of such forms already in the 19th century, either as varietas (var.), forma (f.) or as lusus (lus.). Leslie Lewis presents those descriptions by Philipp Wilhelm Wirtgen (1806-1870), Paul Wilhelm Magnus (1844-1914) and others. Following the Swiss botanist Gustav Hegi (1876-1932) she is presenting a consistent overview on the level of forms:
- Neottia nidus-avis f. pallida: plants with pale yellow flowers
- Neottia nidus-avis f. nivea: plants with snow-white flowers
- Neottia nidus-avis f. sulphurea: plants with sulphur-yellow flowers