Supplementary Figure S1. Schematic drawings of papillate pollen to illustrate hydration levels, papilla configuration, hiatus development, and measurements of morphological characters. A1-4. Stages of hydration (redrawn after VanCampo 1951). A1. Fully hydrated pollen in EV. A2-3. Stages of desiccation. A4. Fully dehydrated pollen. B1-4. Stages of radial splitting, pollen PV (redrawn after VanCampo 1951). C1-6. Papilla configuration in EV. C1. Papilla straight. C2-3. Papilla weakly bent. C4. Papilla sharply bent. C5-6. Papilla indistinct (very small or not detectable). D1-7. Measurements of morphological characters. D1. Papilla width. D2. Leptoma width. D3. Equatorial diameter. D4. Papilla length. D5. Polar axis excluding papilla. D6. Polar axis. Abbreviation: polar view (PV), equatorial view (EV).