Dasylirion serratifolium

Perennial plant with quadrangular leaves. Dasylirion is a group of over a dozen of grassy looking rosette plants native to the southwestern US and northern Mexico. They are not grasses but are related to the Agaves. As they grow older, the base of the several of these species develop into a trunk. When the plant is mature it blooms with hundreds of greenish-white bell-shaped flowers on a tall narrow spike coming from the center of the plant. The plant does not die after blooming. Most Dasylirions are rather resistant to cold and drought.