Hydnocarpus kurzii aka Chaulmoogra

Hydnocarpus kurzii is an evergreen tree, also called chaulmugra. It belongs to the Achariaceae family. Its home range runs from Assam to Peninsular Malaysia. Records also place it in Myanmar, Thailand, Laos, and Vietnam. It grows in wet tropical forests. These sites lie 1,969–5,906 feet [600–1,800 metres] above sea level. People gather it from the wild and grow it. They grow it beyond Asia, in tropical Africa and South America.

Garden guides give a height and spread of 49 feet [15 metres]. Other accounts give heights of 26–66 feet [8–20 metres]. Some trees reach 98 feet [30 metres], beyond the stated garden size. The tree grows at a moderate rate. It keeps its leaves all year. The leaves have an oblong shape. Insects carry pollen between flowers. The tree cannot set seed with its own pollen. Growers raise new plants from seed.

This tree needs the warmth and moisture of the wet tropics. It grows best at daytime temperatures of 28–34°C. Sources give a wider range it can bear: 7–42°C. It grows in full sun or light shade. It needs moist soil that drains well. It accepts sand, loam, and clay soils. Detailed growing notes favour very acid soil, around pH 4.5–5. It prefers 138–256 inches [3,500–6,500 millimetres] of rain each year. PFAF lists USDA hardiness zones 10–12. Its broad size means it needs space when planted.

The seeds yield chaulmugra oil. This was once a key drug for treating leprosy. It helped lead to man-made drugs for the disease. Modern drugs have since replaced much of its old medical use. Folk healers still use it for leprosy and other skin disorders. The oil has chaulmoogric and hydnocarpic fatty acids. Folk healers also make tonics from the bark. Thai healers use roots and seeds for skin complaints. These records describe use as medicine. They do not show that home treatment is safe.

The records give no edible uses. The seeds are poisonous. They contain cyanogenic glycosides, which can cause fatal poisoning. People have also used the fruit to poison fish. Sources warn against eating fish or pigs that ate the seeds. Their flesh may cause nausea and vomiting. The supplied account of its conservation cites a 2010 assessment. That assessment classed it as Data Deficient. This old finding does not show its current conservation status.