Principal components analysis score plot with eigenvalues and the contribution of each PC displayed (left) and loading plot (right) of characters and species in Table 1. Left, red triangles = S. jobsonii, blue circles = S. diversiflorum, black crosses = S. eburneum, pink triangles = S. watneyi, yellow squares = S. succosum and purple asterisks = S. plastisexum. Right, weighted characters labelled and indicated with red arrows. A Seed length B Fruit width C Number of seeds per fruit D Fruit length E Depth of lobing on apical leaves F Depth of lobing on basal leaves G Fruit wall width H Width of basal leaves I Surface area of basal leaves J Calyx lobe length, hermaphrodite flowers K Internode length L Width of apical leaves, M Surface area of apical leaves N Petiole length O Pedicel length in fruit P Corolla diameter, hermaphrodite flowers Q Length of basal leaves R Corolla diameter, male flowers S Length of apical leaves T Plant height U Stem prickle length V Trichome density, abaxial surface of apical leaves W Trichome density, adaxial surface of apical leaves X Calyx lobe length, male flowers. Colours associated with each taxon also used in Figs 2, 3.