Indian Himalayan region (IHR) supports a wide diversity of plants and most of them are known for their medicinal value. Humankind has been using medicinal plants since the inception of civilization. Various types of bioactive compounds are found in plants, which are directly and indirectly beneficial for plants as well as humans. These bioactive compounds are highly useful and being used as a strong source of medicines, pharmaceuticals, agrochemicals, food additives, fragrances, and flavoring agents. Apart from this, several plant species contain some toxic compounds that affect the health of many forms of life as well as cause their death. These plants are known as poisonous plants, because of their toxicity to both humans and animals. Therefore, it is necessary to know in what quantity they should be taken so that it does not have a negative impact on health. Recent studies on poisonous plants have raised awareness among people who are at risk of plant toxicity in different parts of the world. The main aim of this review article is to explore the current knowledge about the poisonous plants of the Indian Himalayas along with the importance of these poisonous plants to treat different ailments. The findings of the present review will be helpful to different pharmaceutical industries, the scientific community and researchers around the world.

The vegetation of the alpine treeline ecotone is among the most vulnerable and sensitive to global climate change. Treelines species respond to global warming through changes in their population structure, regeneration, plant functional traits and shift in their habitat. The present study was carried out on Rhododendron campanulatum D.Don, a typical plant species of the Himalayan treeline ecotone, to understand the variation in population structure, regeneration potential and leaf morphological traits along the altitudinal gradient (3100-3550 m.a.s.l.) in Tungnath, Western Himalaya. We reported the higher seedling (3480 stem ha⁻¹) and juvenile (2210 stem ha⁻¹) density of the species above the treeline at 3400 m.a.s.l. This clearly shows a good regeneration status and indicates the upward shift of the species. Leaf morphological traits such as length, width, and the specific leaf area decreased with increasing elevation but leaf thickness increased with increasing elevation. SLA was higher (71.14 cm²/g; p < 0.001) at 3100 m.a.s.l. located below the treeline than 3550 m.a.s.l. (60.08 cm²/g; p < 0.001)) located above the treeline. The results indicate that the species has large flexibility in the morphological performance and its high level of plasticity in morphological traits may explain its wider niche and ability to survive in harsh alpine conditions.