From Indipedia: India's Wikipedia at OSDD
Common name: Curry Leaf, Kari patta करी पत्ता (Hindi), Barsunga (Bengali), கரிவேப்பிலை Karivepillai (Tamil), Kudianim (Marathi), Kareapela (Malayalam), Bishahari (Assamese)
Botanical name: Murraya koenigii
Family: Rutaceae (citrus family)
Small or medium sized tropical/subtropical tree, most famous for its aromatic leaves that provide curry spice. Curry leaves are extensively used in Southern India and Sri Lanka (and are absolutely necessary for the authentic flavour), but are also of some importance in Northern India. Together with South Indian immigrants, curry leaves reached Malaysia, South Africa and Réunion island. When cooking, the leaves are generally used fresh off of the tree. Outside the Indian sphere of influence, they are rarely found. The yellow "curry powder" that is common in Western countries is actually not curry at all, but a mix of spices intended to mimic the true curry flavor. The yellow color comes from turmeric root. Another plant, Helichrysum italicum, commonly called "curry leaf plant" is actually a small herbaceous annual and completly unrelated to the curry leaf tree.
Medicinal uses: Leaves are digestive, tonic, stimulant, rich in vitamin A and calcium. Leaves are also used for diarrhoea, dysentry and checking vomitting. Bark-paste is antisceptic, applied to skin eruptions. Root extract is taken for relief from renal pain.