(Yellow Flag Iris - 02) The construction of the yellow iris flower is quite interesting: The large yellow petal-like structures with the dark veining are really the 3 sepals. The shorter petal-like structures that partially cover the sepals are really the 3 styles. Three stamens are hidden under the the styles. In the center of the flower are the 3 tiny (by comparison) petals. The total flower measures about 3 inches across.