Use this forum to discuss matters relating to Agave, Beschorneria, Furcraea, Hesperaloe, Hesperoyucca, Manfreda, Polianthes, Yucca and related species. This is where one posts unknown plant photos for ID help.
Possibly a form of Agave obscura. If this plant is as I am suggesting, years ago plants like this with rich, dark green leaves like this used to be known as Agave polyacantha var. xalapensis and originated from the state of Vera Cruz Mexico near the town of Xalapa. I am not certain of this identity but the plant looks similar to that species.