1	Leaves > 1 cm wide	2
–	Leaves < 1 cm wide	3
2	Floral tube ca. 1 cm long, flowers yellow	I. koreana
–	Floral tube ca. 0.5 cm long, flowers white	I. odaesanensis
3	Floral tube > 2.0 cm long, pedicels < 2 cm long	4
–	Floral tube < 1.0 cm long, pedicels > 2 cm long	6
4	Floral tube ca. 6 cm long	I. rossii
–	Floral tube 2–3.5 cm long	5
5	Flowers pale violet, floral tube 2.5–3.5 cm long	I. proantha
5a	Flowering stem to bract < 5 cm tall, leaves < 0.4 cm wide	var. proantha
–	Flowering stem to bract > 7 cm tall, leaves > 0.5 cm wide	var. valida
–	Flowers yellow, floral tube ca. 2 cm	I. minutoaurea
6	Leaves < 3 mm wide, lateral crests flanking median	I. dabashanensis
–	Leaves > 3 mm wide, median crest only	7
7	Style branch lobes 2–3 mm long, sepals ca. 7 mm wide	I. probstii
–	Style branch lobes ca. 6 mm long, sepals ca. 4 mm wide	I. henryi