Pollen grains ofBorago officinalisL. were studied with transmission and scanning electron microscopy. Their main features are: (1) tectum covered with microsculptured gemmae, (2) apertures very elaborated, each of them is composed of a colpus (ectoaperture), a pericolpal cavity which occurs in the foot-layer, a mesoaperture localized within the endexine and a discontinuous endoaperlure displaying an equatorial girdle, (3) a discontinuity between ectexine and endexine which is electron transparent in the young microspore.