The yellow iris, or yellow flag, grows up to 150cm tall and has long grey-green sword shaped leaves. The most striking feature of this plant is its large yellow flowers.
Each flower is 8-10cm across and has large hanging oval petals, called falls, that have purple veins. There are also three or four shorter upright yellow brown standards at the top of the flower.
These flowers can be confused with the yellow bearded iris found in gardens but the yellow iris does not have the spikey beard coning down the centre of the fall