White Margined Agave. This is an old cultivar which has been around for years with a cream-yellow leaf margin. It is much more cold hardy than 'Medio-picta' which even here in zone 8 needs some protection when it hits the teens. It can get quite large with its leaves extending up to 6' or more, and it is also a prolific divider, putting on numerous "pups" around its base. Give it pretty much full sun with excellent drainage. In the photo, it is the plant to the right with 'Medio-picta' in the foreground. Since it is a selection of Agave americana, we can call it a native. If one lives in an area where it is too cold to grow it outside during the winter, it makes a wonderful container plant which would have to be moved inside when the temperatures reach the low to mid 20's. A protected garage would do well for this.
Zones 8-11