The plant in the photo is Yucca Filamentosa ssp. Concava "Variegata". I have both this and Yucca Gloriosa "Variegata". The variegated form of concava can be a little tricky to divide and not as strong a plant as the standard form. The non variegated form of Yucca Fil. Concava can get quiet large with very thick rough long leaves and a cupped leaf end. It only grows in a small area of north eastern North Carolina and may have some ancient Yucca Gloriosa genes mixed in. Yucca Gloriosa "Variegata" does well here in raised areas, but is a very slow grower.