The Himalaya started with mostly immigrant flora but is today home to about 3500–4000 endemic plants that have evolved within a time span of 40–50 million years. It is, however, still unknown as to what factors have been responsible for the development of such high endemism within such a short evolutionary time. It is also unclear as to how plant diversity patterns are structured across the present-day environmental gradients in the Himalaya and whether these diversity patterns will change in the future. My results point towards a positive coincidence between endemic plant species diversification, changes in geo-physical characteristics, and climate in the Himalaya. The present-day plant species richness patterns are hump-shaped, life-form and endemic specific, and scale-dependent. Furthermore, shrublands would emerge as the most successful plant community in future climates, and there would be a need to redesign the Protected Area network due to ensuing climate change in the Himalaya.