Though the species of Tibetan herbs are numerous and their morphology is varied, each species has its own appropriate ecological environment. Hence, each species of plant belongs to a definite type of vegetation. It is essential to understand the type of vegetation that has a significant connection with the distribution, output, exploration, utilization, introduction of fine varieties, and domestication of each one. The main vegetation types are summarized as
Mainly coniferous forest distributed in the eastern and southeastern parts of Mt. Hengduan in a crescent shape. The forests are mainly dragon spruce and cypress, such as Sabina Tibetica, Sabina Saltuaria, Sabina Recurua, Sabina Przewalskii, Sabina Comarcuii, Sabina Pingii, etc. The tender branches and fruits of these predominant species are all used by Tibetan medicine. Taking Tibetica as an example, this kind of forest is distributed mainly in the southeastern border of the Mt. Hengduan area, southern Qinghai and western Sichuan, with bush-clump vegetation and cold altitude meadows as its upper limit, and Abies spp. and Sabina spp. as its lower limit. The bush layer includes Spiraea Mongolica, Spiraea Alpina, Rosa Ameiensis, Lonicera tibetica, Lonicera Hispita, Ribes spp., Berberis Aggregata, Cotonester Multiflorus, Cotenester Multiphyllus, Dasiphora Fruticosa, etc. To the north, since the temperature is low and water is insufficient, cold-resistant and drought-resistant Caragana markedly increases, including Caragana Tangutica, Caragana Maximowiziana, Caragana Kansuensis; while the grass layer includes Kobresia spp., Leontopodium spp., Potentilla Saundersiana, Gueldenstaedtia Diversifolia, Polygoni Viviparum, Artemisia spp., Delphinium spp., Thalictrum spp., Astragalus spp., Viola spp., and Caratlodiscus Kingianus. In these two layers, all the species except Kobresia are used as Tibetan materia medica.
Mainly composed of evergreen broad leaf bush, deciduous broad leaf bush, evergreen coniferous bush, with the former two distributed extensively. Taking the evergreen broad leaf bush as an example, there are Rhododendron Capitatum and Rhododendron Thymifolium, mainly distributed in the northeastern part of the plateau; the accompanying plants include Sitiraea Angustata, Rhododendron Anthoponoides, and Salix spp. Grasses include Polygoni Sphaerostachyum, Rheum Pumilum, Astragalus Jengelianus, Saxifraga Hirculus, Primula Sikkimensis and Gentiana Algida. Most of the vegetation is used as Tibetan materia medica.
Characterized by extensive distribution and high vertical distribution, the high altitude, cold meadow vegetation in the plateau has coniferous forest and cold-resistant bush at the lower limit in the southeastern part, while its upper limit is marked by high-mountain cushion vegetation. Its vertical distribution ranges from 4,200-4,800 m, with extensive distribution from north of Nianqing and Mt. Thangula to the south of the Kunlun Range, with Kobresia spp. as its main component, and its accompanying species, including Gentiana Saxiteramine, dendelion, Anisodus spp., Przewalskii spp., Saussurea spp., Meconopsis spp., Pedicularis spp., etc.
This vegetation falls between the high altitude, cold meadow vegetation and high-mountain, mud-rock stream beach sparse vegetation. The plants are short and small in a semi-spherical or cushion shape and creeper appearance. The cushion vegetation appears as a result of the serious water shortage, low temperature, strong solar radiation and strong wind conditions over the high mountains, and, at the same time, an adaptation derived from long-term natural selection under their harsh growing environment. The average annual temperature for this vegetation is o degrees, with the warmest of being 4-5 degrees in July, while the lowest night temperature may drop to below o degrees, with a day-night temperature difference of 20 degrees. The average annual rainfall is 250-500 mm.
The plants in this vegetation type include Arenaria spp., Among them, Arenaria Musciformis vegetation is mainly distributed over the northern slopes of the Himalayas, Kunlun Mountains, Northern Tibet Plateau and Southern Qinghai Plateau, with an average altitude of 4,600 m. The main accompanying species include Androsace Tapete, Saussurea Gnaphalode, Lagotis Brachystachys, Lagotis Wardii, Lagotis Angustibracteata, Rheum spp., Saxifraga spp., Sedum spp., Saussurea spp., Thylacospeosmi Calspitosum. This type of vegetation has not only numerous species, but also many valuable medicines distributed at this altitude.