Borage (Borago officinalis L.) pollen grains have been ratified as trincellular. The tetrazolium test is a reliable method to evaluate pollen viability in borage. A satisfactory medium for pollen germination and pollen tube growth was achieved in a liquid medium supplemented with 200 g/l of sucrose, 100 ppm of H

BO and 300 ppm of Ca(NO).4HO at pH 7 and 18°C. The pollen tube pathway after effective pollination is described. The importance of temperature in borage pollen biology is proved.