Agapanthus is a genus of herbaceous perennials that mostly bloom in summer. This leads to the Australian common name, Star of Bethlehem, as it blooms just before Christmas. 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.
The inflorescence is a pseudo-umbel subtended by two large deciduous bracts at the apex of a long, erect scape, up to 2 m (6.6 ft) tall. They have funnel-shaped or tubular flowers, in hues of blue to purple, shading to white. Some hybrids and cultivars have colors not found in wild plants which includes bi-colored blue/lavender and white flowers flushed with pink as the blooms mature. The ovary is superior. The style is hollow. Agapanthus does not have the distinctive chemistry of Allioideae.