This longitudinal section of a wheat grain (Triticum aestivum, Family Poaceae) shows the embryo, stained red, with a prominent radicle on the lower side protected by a rootcap and an additional covering called the coleorhiza. The radicle is the first root of a plant, most often well developed in the embryo. In grasses the radicle leaves only a short time after germination and is replaced in function by adventitious roots.