<p>(A-F’) Ring-shaped apertures are common in tetraploid pollen from <i>osd1</i> (A-B’), <i>tam-2</i> (C- D’), and <i>tes</i> (E-F’). Front and back views are shown for each pollen grain (e.g. A and A’). (G-H’) Tetraploid pollen from <i>tam-2; osd1</i> mutants often has abnormal exine patterns that make recognizing apertures difficult. Still, ring-shaped apertures are sometimes visible in <i>tam-2; osd1</i> pollen (H, H’, arrowheads). Scale bars = 10 μm.</p
