Fig. 3

3.1 Mutant Intermedium spike-a (int-a.1). A. Mutant to the left, cultivar Bowman to the right. The upper two-thirds of the spike has fertile lateral spikelets. B. Three mutant seeds with different double awn phenotypes to the left compared with normal Bowman. C. Three triplets of spikelets. The two lateral spikelets are smaller than the central spikelet, but still fertile. 3.2 Mutant Intermedium spike-b (int-b.3). The spike appears similar to the six-rowed spike, but developmental irregularities occur commonly in the lower half of the spike. All lateral spikelets are reduced in size, and their lemma awns are short or reduced to a pointed tip. Commonly, only lateral spikelets in the middle of the spike set seed. Cultivar Bowman is to the right. 3.3 Mutant Intermedium spike-c (int-c.5) to the left compared to Bowman. The lateral spikelets are fairly large and broad, the lemma is often rounded or weakly pointed, awnless or short-awned at the apex. Lower lateral spikelets may develop poorly in some int-c mutants, while seed development may occur in all lateral spikelets of others. Variability in lateral floret development exists among the int-c mutants and environmental conditions can alter expressivity. 3.4 Int-d.12 (middle) compared to hex-v.3 (left) and Bowman (right). Mutations in int-d are semidominant. The awns of lateral spikelets of int-d mutants will vary in length from ¾ to nearly as long as those of the central spikelets. Mutants in int-d are allelic to vrs1 and hex-v [1]. 3.5 Mutants of the Six-rowed spike 4 (vrs4) locus. A. int-e.58. B. mul1.a. Mutants to the left compared to Bowman to the right. 3.6 Two spikes of mutant int-f.19 compared to Bowman to the right. This locus is only represented by the int-f.19 allele. The spike appears six-rowed, but the lateral spikelets are much smaller (less than half the size of the central spikelets). Lateral spikelets are pointed and often have short awns. Seed set occurs in the lateral spikelets in the upper third of the spike. The base of the spike has shortened rachis internodes and appears Erectoides-like [47]. 3.7 Mutant int-h.42 to the left compared to Bowman. Lateral spikelets are enlarged and have an inconspicuously pointed apex, but they do not set seed. Induced mutants show early heading and have an elongated basal rachis internode. The spike appears lax but with shortened rachis internodes at the base [46]. A Bowman backcross-derived line is slightly shorter (5/6 normal) and produces extra spikelets (up to five fertile ones) at several rachis nodes in the lower half of the spike [50]. 3.8 Mutant Lower number of tillers 1 (lnt1.a) compared to Bowman to the right. This mutant is allelic to int-l [51]. Various spike malformations occur in most environments. The spike may have irregular rachis internode lengths. The lower portion of the spike appears denser. Lateral spikelets in two-rowed cultivars are enlarged and have a pointed apex. B is a close-up of the spikes shown in A. 3.9 Mutant int-m.85 to the left compared to Bowman. The spike of int-m mutants is very short due to few rachis internodes and has irregular rachis internode lengths. Lateral spikelets are enlarged and pointed, but they do not set seed. The density of spikelets at the base of the spike is increased. Rachis internodes at the tip of the spike are very short, and the spike appears to have two or three fused terminal spikelets