Abstract
To identify species of fossil Lagerstroemia pollen common in interglacial sediments of Japan, we studied and described the morphology of long and short stamen pollen grains of modern L. indica, L. subucostata, and L. subucostata var. fauriei using light and scanning electron microscopy. Among L. indica, L. subcostata, and L. subcostata var. fauriei, long stamen pollen grains were similar to each other, but short stamen pollen grains were distinguishable. Pollen grains of L. subcostata and L. subcostata var. fauriei were smaller and had thicker pollen walls in the polar area than those of L. indica. Fossil Lagerstroemia pollen grains obtained from interglacial sediments at four localities in Honshu, Japan, inclusive of Last Interglacial sediments, were mostly short stamen pollen grains, and long stamen pollen grains were few. Short stamen pollen grains of fossil Lagerstroemia were morphologically similar to those of modern L. subcostata and L. subcostata var. fauriei. Considering the plant macrofossil record in Japan and the pollen morphology of modern Chinese species, Lagerstroemia distributed widely in central Honshu during Pleistocene interglacial stages is referable to L. subcostata or L. subcostata var. fauriei.
