Fig. 1. The lineage of cell clones and plants regenerated from C^– leaf and C^– pith tissues. Clones were obtained by plating cell suspensions in soft agar and marking colonies of single-cell origin. C^– leaf clones L113N and L201N and C^– pith clone P278N were derived from different plants in separate experiments. C⁺ variants were obtained by selecting for growth on low-cytokinin medium. S₀ generation plants regenerated from subclones were selfed to obtain the S₁ generation. The patterns of segregation for the C⁺ leaf phenotype are shown in Table 1. The origins of homozygous mutant lines Hl-1/Hl-2 and Hl-2/Hl-2 derived from subclones L113H-21 and P278H-12, respectively, are indicated. Clones showing the C⁺ phenotype are shaded.