Grasses like barley have one seed leaf and their embryos have only one cotyledon. They have parallel leaf venation, adventitious roots that arise from nodes other than the root, fibrous roots without secondary growth, scattered vascular bundles in their roots, stems, and leaves, flower parts in multiples of three instead of four or five, and flower petals that are usually not joined together. Furthermore, monocots lack secondary cambium and their pollen grains have only one opening or pore (unilocular). Barley exhibits all these monocot characteristics, hence, it is classified as a monocot.