One of the larger varieties in the flower world, lilies come in several cultivars that can make them sometimes difficult to identify. Lily colors include white, yellow, red, orange and multi. In particular, they can be confused with irises because of similar attributes. While the bulb is the most distinguishing characteristic, there are other features that can help you figure out if the flower is a lily.
Observe the number of petals on the flower. A lily has three petals and three sepals (the outermost layer of the flower surrounding the petals).
Look at the leaves on the plant. Lily leaves have parallel veins along the length of the leaves, while other plants usually have veins that branch out from a single source on the leaves.
Look at the inside of the flower to find the stigma. This is found at the center of the flower and holds the stamens (the small sticks that represent the reproductive organs of the flower). The lily's stigma has three distinct sections, which is different from other flowers.
Examine the base of the lily plant to distinguish it from the iris. Lilies grow from the base in a more free, loose direction, while irises grow upright from the base.
Smell the lily flower. It should have a sweet scent that is strong, not as subtle as an iris.