Figure 3.

(a) Number of conduits N and (b) average SE cross-sectional area A versus distance from the holdfast x^∗ in M. pyrifera. Segments (points) from a single M. pyrifera frond are joined by a line; three individual fronds (symbols) are shown. Points in each frond that purely unload from the phloem are dark blue; segments engaging in bi-directional transport are light grey. (c) Relationship between A and 1 − x/l (inverse height). The data fall along the predicted optimum scaling slope (solid blue line) within a 5% confidence interval. All error bars represent s.d. (Online version in colour.)