Root systems in plants

The taproot system of a tobacco (Nicotiana tabacum) seedling is shown on the left. It is a dicot. The taproot developed from the embryonic root (radicle) in the seed, and all branching lateral roots came from the taproot.

On the right is shown a fibrous root system of onion (Allium cepa), a monocot plant. All of the fibrous roots shown are adventitious and have developed from stem tissue. In monocots, no main root can be identified.

Illustrations from: Berg, 1997, Introductory Botany: Plants, People & the Environment, Saunders College Publishing