Agave sebastiana  synonym Agave shawii var. sebastiana  comes from West San Benito  Natividad and Cedros Islands west of Central Baja California. It forms striking greenish blue clumps of 3-5' wide & is hardy to 20-25 Degrees needing very little water once established. The thick  succulent leaves have toothed margins and form a rosette. Tall flower stalks are produced only after about 20 years  producing stunning yellow flowers. After which the parent plant dies and is succeeded by numerous new plants called 'pups'.