is primarily a Mexican species, found in the US only in the Chihuahuan Desert of west Texas, from Big Bend National Park to the border with New Mexico; within the park one well known location is Dagger Flat
, reached by a 7 mile gravel road. Plants are solitary, usually unbranched but large, with a spiky rosette of thick, rigid leaves above a wide trunk; old specimens may reach a height of 15 feet. The yellow-green leaves typically range between 15 and 45 inches in length, and are 2 to 3 inches in width. Leaf margins bear a sparse array of relatively thick white filaments.