Agave can be perennial or monocarpic succulents, forming rosettes of usually rigid, fleshy, spiny-edged leaves, with funnel-shaped flowers in racemes or panicles often much taller than the rosettes
A. americana is an evergreen perennial forming handsome rosettes of spiny-edged, grey-green leaves. Panicles to 8m in length, of greenish-yellow flowers 8cm in length, are produced only by old plants