The Parts of a Corn Seedling (Zea mays, Monocotyledon)

Diagram of three parts of corn seedling: root system, coleoptile, and first foliage leaf

Monocotyledon: Monocotyledon embryos have one cotyledon that absorbs food. Monocots usually have narrow leaves with parallel veins, and flower parts in multiples of three. They are mostly herbaceous (non-woody) and include grasses, lilies, and orchids. 
Root system: The part of a plant that is usually below ground, anchors the plant, and absorbs water and minerals. 
Coleoptile: A sheath enclosing the actively growing part of a grass.