Agapanthus

Agapanthus is a genus of herbaceous perennials that mostly bloom in summer. The leaves are basal, curved, and linear, growing up to 60 cm (24 in) long. They are rather leathery and arranged in two opposite rows. The plant has a mostly underground stem called a rhizome (like a ginger 'root') that is used as a storage organ. The roots, which grow out of the rhizome, are white, thick and fleshy.

Agapanthus praecox can be grown within USDA plant hardiness zones 9 to 11. In lower-numbered zones, the rhizomes should be placed deeper in the soil and mulched well in the fall. Agapanthus can be propagated by dividing clumps or by seeds. The seeds of most varieties are fertile. Several hundred cultivars and hybrids are cultivated as garden and landscape plants. Several are winter-hardy to USDA Zone 7.

Source: Wikipedia