closed African lily

A clump-forming herbaceous perennial 90-150cm or more high with deciduous, rather upright, strap-shaped leaves, up to 70cm long and 2-3cm across, and stiff, upright stems topped by umbels, 10-15cm across, of hanging flowers, 2.5-4cm long, in late summer and early autumn; the flowers are in shades of blue, often purplish and sometimes very dark in colour, and are tubular with the segments barely open at the mouth