Pollen tube observation is an essential experiment in high school biology; however, in actual laboratory settings, its reproducibility is strongly influenced by pollen viability and agar medium conditions. This study aimed to establish reliable methods for pollen selection and storage, as well as to propose culture conditions that facilitate understanding of pollen germination and tube elongation. Two ornamental Commelinaceae species, Tradescantia reflexa and Gibasis geniculata, were used. Because self-pollination can occur even at the bud stage in Commelinaceae, pollen was collected at three stages: bud, anthesis, and post-anthesis. Germination rate and pollen tube elongation were compared under different sucrose concentrations (0, 5, 10, and 15%) and in the presence or absence of boric acid and calcium. In addition, germination of fresh pollen was compared with that of frozen pollen stored at −20°C and −80°C. In both species, pollen collected at anthesis showed the highest germination rates. Optimal germination and tube elongation were observed at sucrose concentrations of 10–15%, and the addition of boric acid and calcium further enhanced both germination and elongation in both species. In contrast, frozen pollen exhibited markedly reduced germination rates in both species. These results indicate that the use of fresh pollen combined with appropriate medium conditions, including the effects of boric acid and calcium, enables stable and reproducible pollen tube observation in classroom settings.
