A herb. It is a perennial plant 30-45 cm high. The roots are sometimes fleshy with tubers near the tip. The leaves are strap shaped. They are 25-65 cm long by 0.8-2 cm wide. They are stiff and 9-11 veined. The flowers are in spikes densely packed and violet or purple. These are 8-45 cm long with many flowers. The flowers occur in clusters of 4-8. The fruit are black berries. They are round and 6-7 mm across.