Fig. 2.

Example images from pollen tube analysis (si, stigma; st, style; h, hairs; o, ovule). (A) Incompatible combination from self-pollination of S. whiteana; arrows indicate that growth of pollen tubes has terminated in the upper parts of the styles (ovules have been removed from the styles). (B) Compatible combination from S. aria pollination of S. whiteana; arrows indicate pollen tube growth continues into the base of the styles. (C) Typically swollen tips of pollen tubes (arrows) that have ended incompatibly in the style of a self-pollinated S. whiteana. (D) Compatible pollen tubes (arrows) in the base of the style from S. leighensis pollinated by S. porrigentiformis. (E, F) Pollen tubes (arrows) that have penetrated ovules of S. whiteana pollinated by S. aria. Scale bars: (A, B, E, F) = 1 mm; (C, D) = 0·2 mm.