Del Rio and the northern reaches of Big Bend National Park
define the range of yucca thompsoniana
, found only in this small area of far west Texas, close to the Rio Grande. Formerly known as yucca rostrata, this is quite a large-growing plant, forming a thick stem and becoming tree-like, up to 8 feet tall. The light green leaves (yellow or reddish at the edges) are moderately long (up to 17 inches), narrow (half an inch or less across), thin, flexible and mostly flat. The tips are pointed but lack a true spine. There are no white fibers along leaf edges. Mature plants branch, but only a few times; most old specimens have just two or three stems.