Flowers of <em>Oenothera hookeri</em> Torr. et Gray, <em>Oe. brevistylis</em> and <em>Oe. lamarkiana</em> de Vries were pollinated after anthesis by insects. <em>Oe. biennis</em> L., <em>Oe. suaveolens</em> Desf and sulfurea were selfpollinated in the buds. Pollen morphology was slightly different: <em>Oe. hookeri</em> have regular, triporated pollen, often germinating through two pores; in <em>Oe. suaveolens</em> many pollen grains had callose patches on the intine; in <em>Oe. brevistylis</em> tetraporated pollen were more often than in other species; in <em>Oe. lamarckiana</em> many pollen grains were empty; in <em>Oe. biennis</em> and <em>Oe. suaveolens</em> pollen grain size and viability varied. The pollen tube growth and fertilization were similar in 5 species and can be considered as typical for <em>Oenothera</em>. In the ovary pollen tubes branched and changed their growth direction. Near micropyle they formed short branches to the inner integument. In the nucellus the pollen tube became swollen.