Classification of Taxus genus of the Taxaceae family of trees and shrubs is characterized alternately as notoriously difficult or controversial with the species described being discouragingly similar. Depending on the taxonomic authority consulted, the genus contains anywhere from one species with numerous varieties to 24 species with 55 varieties. These are distributed across northern temperate and subtropical regions as far south as El Salvador in Central America and Sumatra in South-East Asia. The species are classified into three groups by differences in leaf epidermal and stomatal features listed below:

1. The wallichiana group with 11 species occurring from central Himalayas to Indonesia and Phillippines, in North America, in the Pacific northwest and from Mexico to Central America with an isolated occurrence in Florida. There are two subgroups namely wallichiana and chinensis within this group.
2. The baccata group with nine species in temperate Eurasia, Northern Africa and eastern North America. There are two subgroups namely baccata and cuspidata under this group.
3. The sumatrana group with four species overlapping in distribution with the wallichiana subgroup in Asia.

Most species of Taxus are found in the understorey or subdominant canopy of moist temperate or tropical mountain forests. Elevations range from near sea level in northern stations to 3000 m in tropical forests.

T. brevifolia is a slow-growing shrub/tree found in the forests of Northwest Canada (British Columbia) and the United States (Washington, Oregon, Montana, Idaho and North California).

T. wallichiana is wide ranging in Asia occurring in Afghanistan, Bhutan, China, India, Indonesia, Malaysia, Myanmar, Nepal, Pakistan and Vietnam. T. wallichiana is said to differ from European T. baccata in the longer leaves, which are generally not abruptly cuspidate and may only merit sub-specific rank. The species in the Phillippines and Indonesia is said to be T. sumatrana and that in Vietnam T. chinensis var mairei. The population of Taxus in Yunnan is that of T. wallichiana var.yunnanensis.

The Asian Taxus species occurs from lowland to montane zones in cool climates with moderate to high evenly distributed rainfall. The North American species (T. brevifolia in Western North America, T. globosa in Mexico and Central America) are scattered trees of the understorey of conifer and broadleaf forests and along riverbanks and ravines.

In India Taxus species occurs in the northern states of Jammu and Kashmir, Himachal Pradesh, Uttaranchal, Sikkim, Arunachal Pradesh, Assam, Manipur and Meghalaya. Preferred habitats for T. wallichiana in Uttaranchal are deeply shaded, moist and sheltered areas such as gorges. This species occurs naturally in Nanda Devi Biosphere Reserve, Garhwal Himalayas, particularly in the north and northwest slopes.

Ongoing research and development in the technology for extracting and synthesizing paclitaxel and other taxanes has widened the range of Taxus species from which these compounds can and are being extracted. These include the European Yew, T. baccata, a widely distributed species and also a common ornamental plant, and the North American species, T. canadensis, for which commercial propagation trials for taxane production are underway.