Flowering plants are divided into two major groups, the dicots and the monocots. The names of the two groups are based on the number of cotyledons found in the seed embryo. Cotyledons are the seed leaves produced by the embryo. Monocot seeds contain one cotyledon. Dicot seeds contain two cotyledons. 

Bean seeds are members of the dicot group and therefore have two cotyledons. Maize seeds are members of the monocot group and therefore have one cotyledon. 

Monocot and dicot seeds are also different in several other ways:

Monocots

• have pollen with a single pore
• have flower parts in multiples of three
• have parallel leaf veins
• have scattered stem vascular bundles
• show an absence of secondary growth

Docots

• have pollen with three pores
• have flower parts in multiples of four or five
• have reticulated leaf veins
• have vascular bundles in a ring
• show the presence of secondary growth