A seed is a mature, fertilized ovule. The seed (of a dicot plant) is made up of a seed coat (for protection), an embryo, and the nutrient-rich tissue called the endosperm (or cotyledon). The seed embryo is actually a miniature root and shoot. Once the seed is protected and enclosed in a seed coat, it ceases further development and becomes dormant. It is interesting to note here that although the seed is not growing, it still “breathes,” needing oxygen in order to stay viable enough to eventually grow. When it does begin to grow, the embryonic root (or radicle) is the first organ to emerge from the germinating seed (see below for more about the radicle).