Endemic to northern Mexico and southern USA where there are very few locations which are threatened by grazing and fire
USA, W Texas, described from two trees in the Davis Mountains and a collection made in 1931 in the Guadalupe Mountains. Zanoni & Adams (1979) cite a collection from Sonora, Mexico (T. A. Zanoni 2872, CS, n.v.) under this taxon. Other scattered trees probably exist in canyons of the semiarid mountains in the region. Adams (2011) has given a map with points in Arizona and New Mexico, as well as western Texas and one locality in NE Sonora, Mexico
Whilst more specimens are being discovered, some far distant from the original trees in Trans Pecos Texas, this variety (or form) of Juniperus deppeana remains very rare, mainly known from large, solitary trees
Habitat and Ecology
This variety is found in rocky soils on mountain slopes and in basins, usually in grassland. Found at an altitude of 1800–2000m.
Critically Endangered D
For a long time this taxon was only known from the type, a lone tree in the Davis Mountains of Trans Pecos Texas. Later, some more trees were found in the area, but now Adams (2011) shows occurrences in Arizona, New Mexico and one locality in NE Sonora, Mexico. The number of mature trees is very limited and regeneration is almost absent. Despite the increase of known trees due to intensive surveys, it is still Critically Endangered under criterion D.
There is an apparent lack of sufficient regeneration possibly due to fire and overgrazing.
Some trees are found within protected areas or are protected by landowners.