Developmental changes in leaf shape and landmarks. A, Leaves sampled along a shoot, from tip-to-base. B, Same leaves in A except scaled to leaf length. The reciprocal relationship between developmental stage (Sn), sensitive to leaf ontogeny, and leaf number (Ln), sensitive to heteroblastic changes in leaf shape, is shown. C, From the first four developmental stages (S1–S4) and leaf numbers (L1–L4) shown for the shoot in A and B; the thickness of veins is highlighted. Note the dramatic decrease in vein thickness through progressive developmental stages (Sn) and leaf numbers (Ln). D, Shape information captured in leaves using landmarks. E, Twenty-one landmarks used in this study capture leaf shape and vein patterning and thickness. Red indicates midvein, orange distal vein, and yellow proximal vein. Darker shades indicate branching veins. Numbers indicate order landmarks were placed. Developmental stage indicated by purple (S1) to green (S10) and leaf number indicated by red (L1) to blue (L10) transitions.