Identification of invasion hotspots that support multiple invasive alien species (IAS) is a pre-requisite for control and management of invasion. However, till recently it remained a methodological challenge to precisely determine such invasive hotspots. We identified the hotspots of alien species invasion in India through Ecological Niche Modelling (ENM) using species occurrence data from the Global Biodiversity Information Facility (GBIF). The predicted area of invasion for selected species were classified into 4 categories based on number of model agreements for a region i.e. high, medium, low and very low. About 49% of the total geographical area of India was predicted to be prone to invasion at moderate to high levels of climatic suitability. The intersection of anthropogenic biomes and ecoregions with the regions of 'high' climatic suitability was classified as hotspot of alien plant invasion. Nineteen of 47 ecoregions of India, harboured such hotspots. Most ecologically sensitive regions of India, including the 'biodiversity hotspots' and coastal regions coincide with invasion hotspots, indicating their vulnerability to alien plant invasion. Besides demonstrating the usefulness of ENM and open source data for IAS management, the present study provides a knowledge base for guiding the formulation of an effective policy and management strategy for controlling the invasive alien species.

In spite of its importance in nation-wide conservation planning, comprehensive information on geographic distribution of threatened plants in India is lacking. Even the threat status of these plants is ambiguous and the country's effort to conserve them is not widely known. A critical analysis of these aspects is essential for identifying gaps in threatened plant conservation. Keeping these in view, we present a review of the existing knowledge on geographic distribution pattern of threatened plants of India, their threat status, and conservation action undertaken to recover these species. Using the available data, we unravel patterns of distribution of these threatened plants in different states of India. When ranking of the families was done based on the total number of species under different threat categories, Orchidaceae ( 644), Fabaceae (185), Poaceae (164), Rubiaceae (103), Asteraceae (88), Euphorbiaceae (72), Asclepiadaceae (62) and Acanthaceae (60) constituted more than half of the total threatened plant species of India. A review on conservation efforts so far undertaken in different parts of the country revealed that the biodiversity-rich phytogeographic regions such as the Himalayas, North East India, and Andaman and Nicobar Islands had lesser conservation efforts in comparison to the Western Ghats, Vindhyas and Peninsular regions of India. The skewed distribution of threatened plants in different states did not truly reflect their absolute presence or absence; rather it is the result of incomplete survey because of the difficult geomorphological and associated geo-climatic conditions, tough terrain and remote locations. In addition, the current data on threatened plants suffer from methodological shortcomings such as classification without using the population data that are so crucial in modern day threat classification, and lack of long-term observational data. The review emphasizes the use of modern tools such as ecological niche modelling for population inventory, area of occupancy and extent of occurrence, and trends in population size and regeneration for precise threat classification conforming to globally accepted methods (e.g. IUCN version 3.1). The works undertaken through the support of Department of Biotechnology, GoI for conservation of 156 threatened plant species under different disciplines of conservation biology during the past three decades have also been compiled and reviewed. A successfully tested protocol following an integrated approach for threatened species conservation is recommended for future conservation action.

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Assigning threat status to a species is essential for prioritization of species under any conservation programme, and therefore, a pre-requisite for species conservation. In India, due to inadequate data, threat status has not been assigned to several plant species, although their population sizes are quite small and they are considered important from conservation point of view. Besides, there is a need for reassessment of threat status assigned by various agencies using updated data on population size, number of mature individuals, area of occupancy, and geographic extent of occurrence. This is crucial as the natural habitats as well as populations of such species are being affected by anthropogenic activities, exotic species invasion, and climate change. In the present study, we assessed the threat status of 59 selected plant species following the IUCN criteria (ver. 3.1). The species were selected after consultation with various experts throughout the country. Field surveys were carried out in various ecoregions of India to locate the species. Population size and number of mature individuals were enumerated following quadrat/plot-based sampling. The exogenous and endogenous factors leading to decline in population and rarity were identified based on field observations as well as laboratorybased seed viability and germination tests. Based on these studies, 20 species were classified under critically endangered category, 21 under endangered, 11 under vulnerable, five under near threatened, and one species each under data deficient and least concern category. Threat assessment for 41 species was done based on number of locations and geographical range of occurrence, while for 18 species it was done based on restricted population and number of mature individuals. Over-exploitation and habitat degradation or loss were the dominant exogenous factors leading to decline in natural populations of the selected species. The major endogenous factors that lead to population decline and species rarity were low seed viability and germination, long dormancy period, less seedling recruitment, low population size, habitat specificity and narrow niche leading to restricted distribution.

Categorization of species under different threat classes is a pre-requisite for planning, management and monitoring of any species conservation programme. However, data availability, particularly at the population level, has been a major bottleneck in the correct categorization of threatened species. Till date, threat assessments have been mostly based on expert opinion and/or herbarium records. The availability of primary data on distribution of species and their population attributes is limited in India because of inadequate field survey, which has been ascribed to resource constraints and inaccessibility. In this study, we demonstrate that ecological niche modelling (ENM) can be an economical and effective tool to guide surveys overcoming the above two constraints leading to the discovery of new populations of threatened species. Such data lead to improved threat assessment and more accurate categorization. We selected 14 threatened plants comprising 5 trees (Acer hookeri Miq., Bhesa robusta (Roxb.) Ding Hou, Gynocardia odorata Roxb., Ilex venulosa Hook. f. and Lagerstroemia minu-

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Aconitum tawangense, a new species from Tawang, Eastern Himalaya is described and illustrated here. This newly described species differ in the shape, size and vestiture of the sepals from its allied taxa A. assamicum and A. orochryseum. Other distinguishing characters include the colour of the petals and number of the carpels. The species was also assessed for its threat status.