Cereal grass and Indian corn

Cereal grass noun - Grass whose starchy grains are used as food: wheat; rice; rye; oats; maize; buckwheat; millet.

Indian corn and cereal grass are semantically related. In some cases you can replace phrase "Indian corn" with "Cereal grass", this phrases are similar.

Indian corn noun - Tall annual cereal grass bearing kernels on large ears: widely cultivated in America in many varieties; the principal cereal in Mexico and Central and South America since pre-Columbian times.

Cereal grass and Indian corn are semantically related. You can use "Cereal grass" instead a noun phrase "Indian corn".