According to the University of California Museum of Paleontology, the major morphological differences between monocot and dicot flowers include the number of cotyledons, pollen structure, number of flower parts, leaf veins, stem vascular arrangement, root development and secondary growth. The actual basis for differentiating the two classes of angiosperms is the number of cotyledons in the embryo.
The cotyledons absorb nutrients from the seed until the seeding is capable of producing its first true leaves and start photosynthesis. Most dicots are descendants of a plant that developed three furrows or pores in its pollen, known as triporate. On the other hand, monocots have a pollen with a single furrow or pore through the outer layer, known as monosulcate. The number of parts of monocot flowers is typically divisible by three, whereas dicot flowers have parts in multiples of four or five.
The University of California Museum of Paleontology points out that a number of major leaf veins run parallel along the length of the leaf in monocots. Dicots have vascular bundles that are arranged within the stem to form a cylinder and appear as a ring of spots when the flower is cut across the stem. Monocots have vascular bundles that look scattered through the stem.