Agave parryi sp. neomexicana:

Very winterhardy Agave till -29°C.
Origin: dry deserts of southern New Mexico and west Texas.
Agave neomexicana makes rosettes of 30 cm long, blue-green leaves, usually accompanied by suckering offsets around the base of the mother plant.
An elegant, drought-tolerant specimen for the hot rock garden.
Dry winter soils are the key to success in colder climates.