Abstract
Cephalanthus occidentalis L. is protandrous and presents pollen secondarily on the stigma surface. Because self‐pollen is present on the stigma, the degree of selling vs. outcrossing in this species will depend on 1) the phenology of pollen presentation and stigma receptivity; 2) whether the species is self‐incompatible; and 3) the rates of self vs. crossed pollen tube growth. This study describes floral morphology and phenology, self‐incompatibility, and pollen tube growth rates in self‐ and crosspollinations of C. occidentalis. Light and scanning electron microscopy were used to study stigma morphology after flower opening, while controlled pollinations tested for incompatibility. Stigmas were unreceptive initially but became receptive by the second day after flower opening. Ninety‐two percent of cross‐pollinated flowers set fruit, compared to 12% fruit set in self‐pollinations. Pollen tubes from selfed and out‐crossed pollen initially had similar growth rates. Out‐crossed pollen tubes began to grow rapidly ca. 5 hr after pollination of a receptive stigma, whereas selfed pollen tubes ceased growth or grew slowly after this time. Pollen tubes from out‐crossed pollen grew the length of the style within 24 hr after pollination, while selfed pollen tubes were inhibited at the stigma‐style junction. Our results indicate that C. occidentalis has selfincompatibility, in addition to protandry and secondary pollen presentation. Protandry allows removal of self‐pollen from the unreceptive stigma, while self‐incompatibility prevents fertilization by unremoved self‐pollen.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.