Sahyadri, the north western ghats of India is blessed with rich bio-diversity. Threes are the most important elements of our forest wealth. Prevailing identification system of trees based on flowers was devised by the famous biologist Carl Linnaeus. Threes are difficult to identify from flowers since flowering is sporadic and in remote canopies. The leaves are omnipresent and accessible. This leaf-based key provides a simple navigation for identification of almost all tree species of north western ghats of India. Pictorial glossary makes the key user friendly. Species are illusrated with close up images of leaves arranged in groups of dominant families. Key features and ecological data make this a handy field guide for Sahyadri trees. Mangrove trees and a few urban trees are also included. A Chapter on tree-butterfly association is a novel addition. The tree identification will help in documentation and preservation of forest wealth of Sahyadri, the bio-diversity hotspot. Contents: 1. Introduction. 2. Pictorial Glossary. 3. Text glossary. 4. Sahyadri Map. 5. Grouping of trees. 6. Key for dominant families. 7. Key for Forest trees. 8. Key for Mangrove trees. 9. Key for Urban trees. 10. Anacardiaceae. 11. Annonaceae. 12. Apocynaceae. 13. Bignoniaceae. 14. Boraginaceae. 15. Clusiaceae. 16. Combretaceae. 17. Ebenaceae. 18. Euphorbiaceae. 19. Lamiaceae. 20. Lauraceae. 21. Leguminosae. 22. Malvaceae. 23. Meliaceae. 24. Moraceae. 25. Myrtaceae. 26. Phyllanthaceae. 27. Rubiaceae. 28. Rutaceae. 29. Sapindaceae. 30. Sapotaceae. 31. Miscellaneous families. 32. Mangrove trees. 33. Urban trees. 34. Scientific names. 35. Excluded species. 36. Local names. 37. References. 38. Tree-Butterfly association.