Justicia adhatoda aka Vasaka

Justicia adhatoda, or malabar nut, belongs to the Acanthaceae family. The name Adhatoda vasica is a synonym for this species. It is native to the Indian subcontinent and Sri Lanka. This upright, woody shrub keeps its leaves through the year. Some plants have few branches, while others form many. It usually reaches about 8 feet [2.5 metres] tall. A separate height entry gives nearly 10 feet [3 metres]. Exceptional plants can reach about 20 feet [6 metres].

This shrub grows in both dry and wet tropical regions. Its wild sites range from damp riverbanks to dry slopes. It also grows on land disturbed by human activity. Its range extends from sea level to about 4,265 feet [1,300 metres]. Gardeners grow it as an ornamental plant. People also gather wild plants for medicine and craft materials. Insects pollinate its flowers.

In cultivation, it prefers full sun but accepts light shade. It grows best with daytime temperatures of 20–27°C. The reported tolerance range extends from 12°C to 32°C. Dormant plants may survive brief cold down to about −1°C. Yet temperatures of 2°C can badly harm young growth. It prefers annual rainfall of 700–1,700 mm. The reported tolerance range is much wider, at 500–4,200 mm. Its preferred soil pH is 6.5–7.5. It can tolerate a pH range of 5.5–8.

People boil the tender young shoots and eat them with salt. This food use does not establish that every part is safe. Leaf extracts have served as fish poisons. Traditional medicine uses the roots, leaves, and whole plant. Ayurvedic and Unani practice uses roots and leaves for several ailments. These include bronchitis, asthma, fever, and jaundice. Other recorded uses address pain, inflammation, and phlegm. These are reports of traditional use, rather than proof of treatment effects.

The plant also provides materials beyond food and medicine. Its leaves yield a yellow dye when boiled with jackwood sawdust. Leaf extracts have uses against insects and fungi. People make beads from the wood and burn it as fuel. They also turn the wood into charcoal. Livestock find the plant unpalatable, and it can colonize disturbed ground. These traits may help it become weedy outside its native range.