The rich biodiversity of eastern Himalaya including Bhutan, comprises most of the aforesaid types of forests except for the ones described at Sl. no. 4, 5 and 6 in preceding paras. The Himalaya is inhabited by a large population, often with their distinct way of life, beliefs, traditions, dialects and cultural heritage (Bennet, 1983). The Himalaya has bestowed them with vast, varied and even endemic plants. The tribals have learnt to utilise indigenous plants in various ways; many of these plants have come to be used in the treatment of different diseases after centuries of trials. The folk medicine of the Himalaya has gifted many plant drugs to modern medicine such as Rauvolfia serpentina (for high blood pressure), Tylophora indica (for asthma and whooping cough), Viola serpens and Adhatoda vasica (for bronchitis), Nardostachys grandiflora (sedative) . (Yonzone & Mandal, 1982). There are number of plants growing in the Himalayan terrain which have great medicinal value (Gaur, Semwal, Tiwari,1983), given in (Table 1.1.and 1.2.) Table 1.1 Western Himalaya (Himachal Pradesh, North Western Uttar Pradesh, Kangra, Garhwal and Kumaon Hills). S. No Plants Part used Medicinal Use 1. Codonopsis ovata Leaves Emollient 2. Myricaria elegans Leaves Applied to bruises and swollen joints. 3. Hippophae rhamnoides Fruits Relieve lung complaints 4. Gentiana stenella Roots Used as febrifuge in periodic fever. 5. Colutea nepalensis Leaves Purgative 6. Ribes orientale Berrium Purgative 7. Senecio jacquemontiana Root Nervine tonic 8. Taraxacum officinale Root Kidney and liver disorder. 9. Onosoma hispida Roots Stimulant 10. Macrotomia benthami Root Eye complaints 11. Rhododendron campanulatum Leaves Common cough and cold 12. Roylea cinerea Leaves Given in periodic fever and for purifying blood. 13. Ajuga bracteosa Leaves Given in syphletic conditions. 14. Arisaema flavum Bulbs Mixed in oil, is applied to eczema and other skin infections. 15. Litsea glutinosa Bark Skin diseases. 16. Boeninghausenia albifera Aerial parts Used to kill flea, lice and other insects. 17. Achyranthes aspera Leaves Cures Leucoderma. 18. Polygonatum verticillatum Roots Nervine Tonic 19. Orchis latifolia Tubers Used as aphrodisiac and nervine tonic 20. Acorus calamus Roots Used in intermittent fever. 21. Swertia chirayita Root Used in intermittent fever. 22. Plumbago indica Roots Used as a powerful sudorific medicine. 23. Bergenia ligulata Roots Employed for dissolving and expelling pieces of stones from kidney. 24. Elaeagnus parvifolia Whole plant Pulmonary infections. 25. Viscum album Whole plant Enlarged spleen. Table 1.2 : Eastern Himalaya (Nepal, Bhutan, Sikkim, Arunachal Pradesh) S. No Plants Part used Medicinal Use 1. Pavetta indica Root Considered as diuretic for visceral obstructions. 2. Guizotia abyssynica Seeds (Oil) Rheumatism 3. Onosoma echioides Flower Cardiac tonic 4. Elaeocarpus sphaericus Fruits Controls epileptic fits. 5. Melastoma malabothricum Bark Used for healing wounds 6. Symplocos paniculata Bark Is astringent, used for gargle for firmness of spongy and bleeding gums. 7. Dendrobium macraei Root stock Is considered as stimulant, demulcent and tonic. 8. Euonymus tingens Root bark Dyspepsia 9. Osbeckia nepalensis Flowers Applied to soothe boils on tongue 10. Hedychium spicatum Roots Considered as stomachic, carminative, stimulant. 11. Iris decora Roots Used against bilious obstructions and cure small sores and pimples. 12. Hypoxis aurea Tubers Applied on injuries and swellings. 13. Hydrangea stylosa Root Severe cold. 14. Aristolochia indica Whole plant Used for stimulation of phagocytosis. 15. Ephedra saxatilis var. sikkimensis Whole plant Asthama 16. Drymaria cordata Whole plant Given for hay fever 17. Rheum webbiana Roots Tonic for convalescent patients. 18. Urtica ardens Young inflorescence Considered as invigorating agent, given after child birth. 19. Skimmia laureola Fruits Gastric pain 20. Myrica esculenta Bark Given as astringent in Cholera.