Thalictrum nainitalense (Ranunculaceae), a new species from the Uttarakhand Himalaya, India

The genus Thalictrum (Ranunculaceae), commonly known as meadow rue, comprises 200 species throughout the world and there are 25 taxa growing in India. While revising the genus in India, we came across a new species collected in Nainital in the Uttarakhand Himalaya. The new species, Thalictrum nainitalense, is differentiated from its closely allied species T. punduanum in its habitat preference for moist shaded stands in Rhododendron arboreum and Quercus oblongata forests, creamy-white flowers, the size of the sepals and stamens, and fusiform, stipitate, hairy achenes. A line drawing, colour plates and a key to the species found in the Uttarakhand Himalaya are provided to aid identification. The status of Thalictrum nainitalense as a species new to science is supported by morphological and molecular data.