Testing the influence of gravity on flower symmetry in five Saxifraga species
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Flower symmetry is considered a species-specific trait and is categorized in asymmetry, actinomorphic symmetry, bisymmetry and zygomorphic symmetry. Here we report on the intra-individual variation of flower symmetry in the genus Saxifraga and the influence of light, gravity and intrinsic factors on the development of flower symmetry. We tested five species—Saxifraga cuneifolia, Saxifraga imparilis, Saxifraga rotundifolia, Saxifraga stolonifera and Saxifraga umbrosa—concerning six flower parameters—angles between petals, petal length, petal pigmentation, angular position of carpels, movement of stamens and (only for S. imparilis and S. stolonifera) the length of the two lower elongated petals in regard to their position towards the stem. Specimens of all species were tested on a vertical clinostat as a gravity compensator, on a horizontal clinostat as a light incidence compensator and on a stationary control. The results show that the angle of incident light has no apparent impact on flower symmetry, whereas gravity affects the angular position of petals in S. cuneifolia and S. umbrosa and the petal colouration in S. rotundifolia. In S. cuneifolia and S. umbrosa, the absence of directional gravity resulted in the development of actinomorphic flowers, whereas the corresponding control flowers were zygomorphic. The development of flowers in S. rotundifolia was not altered by this treatment. The length of the two elongated petals in S. stolonifera and S. imparilis was not affected by gravity, but rather was determined by position of the flower within the inflorescence and resulted in asymmetrical flowers.
KeywordsFlower symmetry Zygomorphy Actinomorphy Saxifraga Pollination
We thank Leonie Sermon and Michaela Krohn for acquisition of data and Andreas Fischbach for support in the botanical garden.
Compliance with ethical standards
The authors declare that they have no competing interests.
- Almeida J, Rocheta M, Galego L (1997) Genetic control of flower shape in Antirrhinum majus. Dev 124:1387–1392Google Scholar
- Citerne H, Jabbour F, Nadot S, Damerval C (2010) The evolution of floral symmetry. In: Kader JC, Delseny M (eds) Advances in botanical research, vol 54. Academic Press Ltd–Elsevier Science Ltd, London, pp 85–137Google Scholar
- Cubas P (2004) Floral zygomorphy, the recurring evolution of a successful trait. Bio Essays 26:1175–1184Google Scholar
- Fukaki H , Wysocka-Diller J, Kato T, Fujisawa H, Benfey PN, Tasaka M, (1998) Genetic evidence that the endodermis is essential for shoot gravitropism in Arabidopsis thaliana. The Plant Journal 14(4):425–430Google Scholar
- Hensel W (1993) Pflanzen in Aktion—Krümmen, klappen, schleudern. Springer Spektrum der Wissenschaft, HeidelbergGoogle Scholar
- Heß D (2001) Alpenblumen—Erkennen, verstehen, schützen. Ulmer, StuttgartGoogle Scholar
- Köhlein F (1995) Saxifragen und andere Steinbrechgewächse. Ulmer, StuttgartGoogle Scholar
- Leins P, Erbar C (2010) Flower and fruit—morphology, ontogeny, phylogeny, function and ecology. Schweizerbart, StuttgartGoogle Scholar
- Prenner G, Bateman RM, Rudall PJ (2010) Floral formulae updated for routine inclusion in formal taxonomic descriptions. Taxon 59:241–250Google Scholar
- R Development Core Team (2008) R: a language and environment for statistical computing. R Foundation for Statistical Computing, ViennaGoogle Scholar
- Salisbury FB (1993) Gravitropism: changing ideas. Hortic Rev 15:233–278Google Scholar
- Schoute JC (1913) Beiträge zur Blattstellungslehre. Réc Trav Bot Néerl 10:153–235Google Scholar
- Vöchting H (1886) Über Zygomorphie und deren Ursachen. Jb wiss Bot 17:297–346Google Scholar
- Weberling F (1981) Morphologie der Blüten und der Blütenstände. Ulmer, StuttgartGoogle Scholar