Khair (Catechu Acacia)

Khair (Senegalia catechu, formerly Acacia catechu, locally khair) is the hardy, thorny legume tree that holds the dry, broken ground of the Pothohar plateau, the Punjab plains, and the lower KPK hills. It is the source of katha, the tannin-rich extract chewed in paan, and of a heartwood as dense and durable as almost anything grown in the country. On a syntropic site it sits in the secondary stratum: a nitrogen-fixing tree that builds soil and shade on poor ground while it grows toward a long-term return in fuel and timber.

Where it thrives

Khair is a tree of the seasonally dry tropics. It grows from sea level to about 1,500 m, takes mean temperatures in the range of 32 to 39 °C, and produces on rainfall anywhere from roughly 500 to 2,000 mm a year.¹ Its native range runs across the Indian subcontinent, including Pakistan, Nepal, and Myanmar, on into southwestern China and Thailand, and it favours mixed deciduous forest, open savanna, and sandy riverbanks.² It does well on well-drained rocky, sandy, or otherwise poor soils, which is exactly why it persists on the eroded slopes and gravel of the sub-Himalayan tracts where richer trees fail.¹ A deep root system carries it through the dry season.

Role in the system

Khair earns its place in the guild as a nitrogen fixer: like other legumes it forms root nodules with soil bacteria that pull nitrogen from the air, feeding the trees around it.² Treat it as a light-demanding secondary tree set among pioneers on hard, dry sites. Its open, feathery crown casts thin shade rather than dense cover, so understorey layers can still carry the short-term yield while the khair builds fertility and stabilises loose ground with its roots. It is thorny, which makes it a useful living barrier against browsing stock at the edge of a planting. Because it is slow and long-lived, it holds the site while faster pioneers come and go.

What you get

The heartwood is the prize. It is comparatively heavy, with a density of 880 to 1,000 kg per cubic metre, and yields katha (catechu), a solid extract that runs 55 to 60% tannins and is used in paan, in dyeing, and in leather tanning.¹ The same wood is a first-rate fuel: sapwood holds about 5,142 kcal per kg and heartwood about 5,244 kcal per kg, and on charring it gives roughly 38% charcoal of very good quality.¹ Offcuts and thinnings burn hot, the durable timber goes to furniture, posts, and farm tools, and the standing tree adds nitrogen, shade, and erosion control across the years it takes to mature.

Cautions

Khair is armed with sharp thorns, so site it where the spines work for you as a barrier rather than against you on a path or a work line. It needs light and resents heavy shade, so do not plant it under a closing canopy. It is slow, and the katha and quality heartwood are a long-term return measured in many years, not a quick harvest.¹

Sources

1. Heuzé, V., Tran, G. et al. “Black cutch (Senegalia catechu).” Feedipedia, INRAE, CIRAD, AFZ & FAO.
2. Useful Tropical Plants. “Senegalia catechu.” Useful Tropical Plants Database.