Very robust tufted perennial forming a large clump. Spreading vigorously from strong yellow underground stems. Broad dark green strap leaves 20-95cm x 2-4cm standing erect. Sheathed at base. Regularly and prominently teethed on margins and midrib of lower surface. Flowers, blue with pale yellow anthers shorter than swollen dark yellow stalk. Many branched flowerhead, generally taller than leaves, with many flowers, petals spreading to bent backwards. Berry shiny, smooth, purple.