Pollen tube growth in pistils of female-sterile and fertile plants ofOenothera mut.brevistylis

Summary Pollination and pollen tube growth was observed in pistils of fertile and female-sterile plants ofOenothera mut.brevistylis. The stigmas and styles of sterile plants were very irregularly formed and additional ovules often developed in the style. The malformations did not inhibit pollen tube growth but made it slower and less efficient. The pollen tubes grew in the ovary but did not find the ovules. Near their tips, pollen tubes branched or meandered without any clear direction. Lack of tropism caused by malfunction of the ovules is postulated in the female-sterile plant.