Stem rounded, not angled or winged:.................................................................................... E. nivulia
Stem angled or winged
Angles not produced into wing, spirally arranged:.......................................................... E. neriifolia
Angles produced into wings
Wings 3-4
wings running straight, sinuate, regularly dentate
Stems green without white bands ,..........................:........E. antiquorum
Stems white wholly or partially
Stems with white bands on faces
Stem apex not cristate (without crowns at tips).......E. lactea
Stem apex cristate (with crowns at tips)..................E lactea cv. Cristata
Stems uniformly greyish white........................................E. lactea cv. White Ghost
wings running spirally, .........................................................................E. tortilis
Wings 5-6, undulate.......................................................................................E. royleana