Dynamics of secondary pollen presentation in Campanula medium (Campanulaceae)
After several decades of research, dynamics and patterns of mating system in floral evolution remain incompletely understood, especially with regards to strategies that combine both outcrossing and selfing, as frequently recorded in the genus Campanula. Data about temporal and spatial dynamics of secondary pollen presentation are still scarce in literature: we investigated them using Campanula medium (Campanulaceae) as case study. Experimental pollinations were conducted under natural conditions, to characterise the breeding system of this species. Effects on stigma opening and stigma receptivity of stylar pollen presence were investigated in manipulated flowers. The temporal dynamics and fitness of male and female functional phases were estimated. Flower visitors and their interactions with sexual parts of the flower were also annotated. C. medium is xenogamous and self-incompatible, with a clear temporal separation between sexual functional phases. Floral lifespan is shortened by experimental outcrossing. Removal of pollen from the style shortened the time span of male function. Pollen viability was highest at the beginning of the anthesis, decreasing during the flowering period, whereas stigmatic receptivity shows an opposite trend. We found a severe pollen limitation in the studied population. Bees were the most frequent floral visitors. In some of these insects we observed stereotyped interactions with the reproductive structures of the flower, in particular with the pollen, exposed along the upper and median portion of the style. Sexual phases in C. medium are inversely correlated and finely spatially and temporally coordinated, since stigma maturation is scalar along its length and depends on pollen presence on the style. Overall, our findings push forward the knowledge on reproductive strategies in Campanula.
KeywordsBreeding systems Flower longevity Plant–insect interactions Protandry Pollen limitation
This study is dedicated to the memory of Maria Ansaldi (1959–2013). The Botanical Garden of Apuan Alps “Pellegrini-Ansaldi” is gratefully acknowledged for the logistic support in carrying out experimental activities. We thank Francesca Angeli, Junior Lacerda, Nico Menchini, Andrea Ribolini, and Romario Tabosa† for their help in field activities. †—deceased.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no conflict of interest.
- Ashman TL, Schoen DJ (1996) Floral longevity: fitness consequences and resource costs. In: Lloyd DG, Barrett SCH (eds) Floral biology. Chapman and Hall, New YorkGoogle Scholar
- Bartolucci F, Peruzzi L, Galasso G, Albano A, Alessandrini A, Ardenghi NMG, Astuti G, Bacchetta G, Ballelli S, Banfi E, Barberis G, Bernardo L, Bouvet D, Bovio M, Cecchi L, Di Pietro R, Domina G, Fascetti S, Fenu G, Festi F, Foggi B, Gallo L, Gubellini L, Gottschlich G, Iamonico D, Iberite M, Jinénez-Mejías P, Lattanzi E, Martinetto E, Masin RR, Medagli P, Passalacqua NG, Peccenini S, Pennesi R, Pierini B, Poldini L, Prosser F, Raimondo FM, Marchetti D, Roma-Marzio F, Rosati L, Santangelo A, Scoppola A, Scortegagna S, Selvaggi A, Selvi F, Soldano A, Stinca A, Wagensommer RP, Wilhalm T, Conti F (2018) An updated checklist of the vascular flora native to Italy. Plant Biosyst 152:179–303CrossRefGoogle Scholar
- Bosma T, Dole JM (2002) Postharvest handling of cut Campanula medium flowers. Hort Sci 37:954–958Google Scholar
- Cavins TJ, Dole JM (2001) Photoperiod, juvenility, and high intensity lighting affect flowering and cut stem quality of Campanula and Lupinus. Hort Sci 36:1192–1196Google Scholar
- Dafni A, Kevan PG, Husband BC (2005) Practical pollination biology. Enviroquest, OntarioGoogle Scholar
- Endress PK (1994) Diversity and evolutionary biology of tropical flowers. Cambridge University Press, CambridgeGoogle Scholar
- Faegri K, van der Pijl L (1979) The principles of pollination ecology. Pergamon Press, OxfordGoogle Scholar
- Gullan PJ, Cranston PS (2009) The insects: an outline of entomology. Wiley, LondonGoogle Scholar
- Hill L, Hill N (2003) The flower gardener’s Bible: time-tested techniques, creative designs, and perfect plants for colorful gardens. Storey Publishing, North AdamsGoogle Scholar
- Kato M, Shimizu H, Onozaki T, Tanikawa N, Ikeda H, Hisamatsu T, Ichimura K (2002) Role of ethylene in senescence of pollinated and unpollinated Campanula medium flowers. Hort J 71:385–387Google Scholar
- Ladd PG (1994) Pollen presenters in the flowering plants - form and function. Bot J Linn Soc 115:165–195Google Scholar
- Lloyd DG (1965) Evolution of self-compatibility and racial differentiation in Leavenworthia (Cruciferae). Contr Gray Herb 195:3–134Google Scholar
- Pignatti S (1982) Flora d’Italia. Ed. Agricole, BolognaGoogle Scholar
- R Core Team (2016) R: a language and environment for statistical computing. R Foundation for Statistical Computing, Vienna. http://www.R-project.org/
- Shivanna KR (2003) Pollen–pistil interaction and fertilization. In: Pollen biology and biotechnology. Science Publisher Inc., EnfieldGoogle Scholar
- Sprengel CK (1793) Das entdeckte Geheimnis der Naturim Bau und in der Befruchtung der Blumen. Friedrich Vieweg, BerlinGoogle Scholar