Agave desmettiana variegata
(This plant comes in a 3.5" pot. You will receive a very similar plant to the one in the picture. It may or may not be blooming at the time of your purchase. The plant is shipped in its pot to prevent any damage to the roots).
Also known as spineless jade agave or smooth agave, is a rosette-forming perennial succulent native to southeastern Mexico. It has a very attractive bright green with yellow variegation along the margins. Spines are very small or nonexistent along the margins. It is also noted for its infrequent but spectacular flowering spikes which appear at the end of each plant's life cycle. Each leaf can grow up to 20-40" long and to 3 1/2" wide is thick, rigid, fleshy and linear-lanceolate with smooth margins and a single reddish sharp terminal spine (to 1/2" long). Each rosette will flower only once between 8-10 years. The plant dies after flowering, but new rosettes formed from the base of the mother plant. The flowering stalk rises up to 8' tall containing terminal clusters of pale yellow flowers typically bloom in spring to early summer (May-June).
Some of the information in this description has been found at desert-tropicals.com, llifle.com and cactus-art.biz