Most of the cultivated forms of geranium (Pelar-gowiwa) may be grouped into four horticultural classes, i.e., (1) zonal geranium, (2) show pelar-gonium, (3) ivy-1eaved geranium, and (4) scented-leaved geranium; the former three are used as ornamertals and the last one as aromatics. In general, geraniums are highly sterile and many of them set few or no seeds. Interspecific hybridization is alm-ost unsuccessful. The present study was underta-kento elucidate the behavior of pollen tubes in inter-and intrapollinations and to presume cross-affinity relationship among several species. After reciprocal crosses were made among different species, the behavior of pollen tubes in the style was observed with the aid of a fiuorescence microscope and fruit-and seed-set was examined.