The Eastern Himalayas Region is characterized by extreme altitudinal variations, and this contribute to its rich biological diversity. It includes Bhutan, north-eastern India, and southern, central, and eastern Nepal. About 1748 plants of about 8000 species of vascular plants are known for their medicinal properties and are found in the Indian Himalaya. However, extreme human interference today has resulted in a threat to tens of thousands of species with extinction. Herbal medicines are becoming popular and this has enhanced the research towards ethnobotanical and ethnomedicinal investigation on herbal products. Consequently, medicinal plants are now under great pressure due to increased demand. Other potential causes for this loss include-habitat specificity, narrow range of distribution, land use disturbance, introduction of non-natives, habitat alteration, climatic changes, heavy livestock grazing, explosion of human population, fragmentation and degradation of population, population bottleneck and genetic drift.
A number of plants with high medicinal value were found in the Himalayas Region (North-Eastern India) that belong to the category of Rare, Endangered, Threatened, Extinct, Vulnerable plants (Red Data Book). This is a big threat to the medicinal world. Meghalaya has 36 medicinal plants species in the ‘Rare’ category followed by Manipur (9), Tripura (3), Mizoram (3) and Arunachal Pradesh (1). Highest number of medicinal plant species in the Endangered category (24) was found in Assam region followed by Meghalaya (4), Mizoram (3) and Arunachal Pradesh (1). Interestingly, while other regions like Manipur, Tripura did not show any medicinal plant species in Endangered category, Assam showed nine medicinal plant species in Threatened category followed by Arunachal Pradesh with one species. Assam showed only one medicinal plant species in Extinct category, while no such category was found in other regions- Manipur, Tripura, Mizoram, Arunachal Pradesh and Meghalaya. Total five medicinal plant species was found in the category of Vulnerable group in Meghalaya, but, no such category was found in regions like Manipur, Tripura, Mizoram, Arunachal Pradesh and Assam.
About 80% of the population in the developing countries depends directly on plants for its medicine (WHO). Out of the 20,000 medicinal plants listed by the WHO globally, India's contribution is 15 – 20%. India is one of the biodiversity hotspots of the richest and highly endangered eco-regions of the world. It contains over 5% of the world’s diversity though it covers only 2% of the earth's surface. The medicinal plants of the Himalayas are threatened due to various reasons such as high demand for essential oils, herbal medicines, and pharmaceuticals, unsustainable harvesting. Other factors like increasing environmental degradation, climate change has increased threat to the Himalayan native flora too. During drug formation if the particular plant that have specific medicinal properties is not available, then in that case, we can supplement it by the nearest plant that has same medicinal properties on the basis of neighbor-joining dendrogram analysis. It is important to identify the region that is best fit for the plant conservation on this. Most of the plants are already included in Red Data Book, therefore, it is very useful to identify those plants that have more medicinal value and can be used in future. These strategies may reduce the heavy pressure on the biodiversity of the medicinal plants, particularly on native plants of Himalayas.