Codonopsis lanceolata aka Bonnet Bellflower

Codonopsis lanceolata is a climbing perennial in the bellflower family. Gardeners know it as bonnet bellflower. Its native range spans the Russian Far East, China, Korea, and Japan. It grows in moist woods on hills and low mountains. In Japan, it also grows along damp forest edges. This plant comes from temperate regions and forms thick underground tubers.

The vine climbs by twining and needs something to grip. In gardens, it reaches about 10–15 feet [3–4.57 metres] tall. Its spread can reach 6 feet [1.83 metres]. The stems die to ground level each winter. Green leaves cluster near the ends of the branches. Each leaf has an oval to elliptic shape. They measure about 0.17–0.25 feet [0.05–0.08 metres] long. The leafy stems can weave through large shrubs. A trellis offers another way to display the vine.

The flowers hang down and have a bell shape. They appear from August to September, adding late-summer interest. Each bloom reaches about 0.1 feet [0.03 metres] long. The outer surface is green with a pale blue-purple tint. Violet spots or stripes mark the inside of each bell. These markings give the flowers detail when viewed up close. The blooms provide the main show above the green leaves.

Grow this vine in well-drained soil that stays moderately moist. It accepts full sun or partial shade. Sandy loam suits it best, though average garden soil can work. A woodland edge or patch of dappled shade also suits it. It is hardy in USDA zones 6–8. Near its cold limit, choose a sheltered site. Winter mulch gives added protection in such places. The plant needs little routine care and is easy to grow. No serious insect or disease problems are reported. Slugs may harm young plants before they become well established. Take care when dividing plants, since they dislike root disturbance.

The roots have a place in Korean cooking. Plants For A Future lists roots and leaves as edible parts. It records raw or cooked use of the roots and young plants. The same source reports no known hazards for this species. That report does not establish safety for every person or pet. It also records traditional medicinal uses for the root. These include use for menstrual problems and blocked milk flow. Such records describe past use, rather than proof of safe treatment.