I hope some of the Lilium growers with more experience than me can tell what causes the "bleaching" of the leaves of some of my Lilium species. They are grown under glass, potted up last autumn in fresh compost and grown medium shaded. The leaves start green but after 1-2 weeks loose the deep green so the veins start to show. Not all my Lilium have it and the younger plants seem more affected than the older. Nutrient difficiency? Too warm? Or, and I hope not but... virus?
First is L. japonicum, a species which grows at low altitude so should need some warmth, second is unknown/unflowered, third is L. lophophorum