Lilium monadelphum, L. szovitsianum and L. armenicum belong to group of yellow flowering Lilium species and they are both often cultivated.
These species come from Caucasus area, so the first two are both described in the Flora of SSSR (4th volume). However, I find the dichotonic key description incomplete, and, based on the key, I am not able to clearly distinguish these species. Lilium armenicum is described by some authors as a variety of L. szovitsianum or as a subspecies of L. monadelphum.
What are your experiences with determination of these species?