Phloem sieve plates in stems of gsl7 mutant and wild-type plants. Images are taken from the batch of gsl7 mutant plants with the largest sieve plate pores. Pore sizes were smaller in two further independently grown batches of mutant plants (Fig. 4). Images were obtained as described for Figure 4. All images are at the same magnification. A, The gsl7 mutant. B, The wild-type, grown under the same conditions and at the same time as the gsl7 mutant plants shown in A. Bar = 5 μm.