The Yellow water iris grows beside ponds and rivers etc.
Rhizomes, up to 4 cm thick and with deep roots form dense masses.
The alternate, basal, linear leaves are over 1 m high and up to 3 cm wide.
Inflorescences, sometimes branched are almost as high as the leaves.
Each can have 1 to a few flowers that are up to 10 cm across.
The erect flowers are on pedicels up to about 6 cm long with 2 basal bracts.
Flowers have 6 tepals with the bases fused to form a tube.
Flowers are mostly bright yellow but range from cream to orange or nearly white.
The downward curving falls are up to 7.5 cm long and the erect standards up to 3 cm.
The base of the falls have radiating brown, purplish or red veins.
The 3 stamens lie under the petaloid styles that are up to 4 cm long.
The anthers are under the stigma which is at the base of the 2 lobes of the styles.
The inferior ovary of 3 fused carpels has 3 locules with numerous ovules.
The 6-ribbed capsules, up to 6 cm long contain many white ovules.
When mature the seeds in each locule are closely stacked on top of each other.
The flattened seeds are pale brown.