Native to the Himalayas and China, these plants have showy trumpet- shaped flowers similar to those of their trumpet vine relatives (Bignonia, Campsis, and the like). Flowers are large for the size of the plant. Many species are coming into cultivation, but only the following two have reached North American gardens in any num- bers. Leaves are 28 in. long, divided featherwise into leaflets. Plants are deep rooted and need reasonably deep soil and excellent drainage. In Upper South, mulch plants after the soil has frozen (to prevent ground from heaving). Protect from slugs and snails.
I. arguta. HIMALAYAN GLOXINIA. Zones LS, CS; USDA 8-9. Can be treated as annual in colder areas, since it will bloom first year from seed if started in earliest spring. Grows erect to 5 ft. tall and 3 ft. wide, or sprawls to 3 ft. tall and 5 ft. wide; somewhat shrubby at base. Leaves divided into 4 to 12 leaflets, each up to 2 in. long. Blooms in spring and summer; inflorescences have 5 to 20 pink or white, 112-in.-long flowers. Effective leaning over walls or spilling down slopes. Self-sows but not a pest.
I. delavayi. HARDY GLOXINIA. Zones US, MS; USDA 6-7. To 2 ft. high, 1 ft. wide. Like I. arguta, has divided leaves and trumpet-shaped flowersbut in other respects, it is entirely different. Grows from a carrot-shaped perennial root and forms a rosette of foot-long leaves, each divided into many leaflets. The foot-tall flower stalk is topped by 212 flowers that are 3 in. long and wide, rosy purple outside, yellow and purple within. Blooms in late spring, early summer. Division is difficult. 'Bee's Pink' has mauve-pink blooms; those of 'Snowtop' are white.