The ear of a wheat plant is made up of two rows of spikelets (Figure 4). The spikelets contain the florets and are arranged on opposite sides of a central rachis (Setter & Carlton 2000b) . The spikelet is surrounded by two sterile glumes which enclose up to 10 individual flowers (florets). The florets are enclosed by a lemma and a palea. The tip of the lemma may be extended to form an awn in some varieties. The florets are composed of the carpel (the ovary and the stigmas) and three stamen and anthers (Setter & Carlton 2000b). Each anther consists of four loculi enclosing the pollen grains (Kirby 2002).
Figure 4: The structure of the wheat ear showing the structure of the spikelets and florets. Reproduced in original form with permission (Setter & Carlton 2000b).
3.2.1 The caryopsis
The caryopsis or grain of the wheat plant is made up of the bran coat and the endosperm surrounding the embryo (Setter & Carlton 2000b). The bran coat consists of three layers, the pericarp, testa and aleurone. The endosperm makes up 83% of the wheat grain and stores the starch and protein important both for the developing plant and flour production (Setter & Carlton 2000b). The embryo makes up only a small percentage of the grain but contains the root radicle and the shoot apex surrounded by the coleoptile. The scutellum separates the endosperm from the embryo (Setter & Carlton 2000b).