Yellow flag iris forms dense growth along riverbanks and the fringes of ponds, competing with indigenous species and altering water flow. It is a perennial moisture-loving plant with yellow flowers and long, strap-like leaves. It reaches a height of 100-150cm.
Leaves: Long, strap-like leaves, green to bluish-green and erect, with the upper part bending over. Leaves 1m long and 30mm wide.
Flowers: Large yellow flowers with three narrow and three broad lobes 70mm long and 40mm wide.
Fruit/seeds: Glossy green three-angled capsules which are 40-80mm long.