Functions of the main, lateral and additional roots.

The main root is the first organ that appears when the seeds germinate. It grows down into the soil, anchoring the seedlings. In gymnosperms and dicotyledons (angiosperms with two seed leaves), the main root grows downward, while lateral roots grow to the side of it, forming a root crop system. In some plants, such as carrots and turnips, the root also serves as a food storage. Some roots, called accessory roots, arise from an organ other than the root — usually the stem, sometimes the leaf. They are especially abundant on underground stems such as rhizomes, tubers and tubers, and allow many plants to vegetatively propagate from stems or leaves.