Strobilanthes cusia aka Assam Indigo

Strobilanthes cusia is in the Acanthaceae family. People call it Assam indigo and maigyee, among other names. Its native range runs from the eastern Himalaya to southern China. It also reaches Indochina and Taiwan. Records list India, Bhutan and Bangladesh. They also list Myanmar, Thailand, Laos and Vietnam. It is not native to Britain or Ireland. In the wild, it grows on hills and in damp woods.

This plant is a perennial, which grows for several years. It forms a clump of upright stems that branch. The stems can turn woody, at least near their base. Sources give different heights. One gives about 2 feet [0.6 metres]. Another lists 3.3 feet [1 metre]. A broader account gives 1.6–4.9 feet [0.5–1.5 metres]. The lower figures serve as a guide to its garden size. The plant is monocarpic: it dies after it flowers. It may grow for several years before it blooms. It does not return to bloom each year.

Grow it in moist soil, in sun or part shade. It accepts sand, loam and clay soils. The soil can be mildly acid, neutral or mildly alkaline. Wild plants grow on wet ground and in moist woods. Records cover warm parts of southern China and tropical Indochina. Wild plants grow at heights of 328–6,562 feet [100–2,000 metres]. These records do not show how much frost it withstands. The sources list garden beds as a place to grow it. They also state that growers can raise it from seed.

The leaves yield a blue indigo dye. This use once led to large-scale crops in China and India. Man-made dyes later took the place of much of that crop. People still grow it on a small scale. They also gather plants from the wild. Growers can pick young shoots two or three times each year. Its recorded worth lies in dye and use in folk medicine. The sources name no set role for it in planting for looks.

Folk medicine uses both the roots and leaves. Accounts list uses for fever and inflammation, or swelling. They also list treatments for mumps and sore throats. Some aim to treat skin complaints. These records show past use, not proof of safe treatment. The sources list no known food uses or hazards. This does not prove that the plant is safe to eat. They give no pest or disease accounts specific to this species.