Together with shape, colour, and individual flower phenology, floral odours are considered to have evolved and diversified in response to the preferences of flower visiting animals. This relationship is reflected in the widely adopted classification of flowers with different pollination syndromes (Delpino 1868-1875, Müller 1881, Knuth 1898-1905, Vogel 1954, Kugler 1970, Faegri & van der Pijl 1979).

Floral scent is often used in chemotaxonomic studies (e.g. Gerlach & Schill 1989, Dahl et al. 1990, Knudsen 1994, Knudsen & Mori 1996), or in studies dealing with pollination syndromes (Gerlach & Schill 1991, Knudsen & Tollsten 1993). Pollinator attractants are recognised in a number of diverse chemical classes, particularly terpenoids, hydrocarbons, esters, simple alcohols, aldehydes, and fatty acids (Kite et al. 1991, Knudsen et al. 1993).

Many Silene and Dianthus species are known for their well scented flowers. In night-flowering species floral scent plays an important role for the attraction of moths and hawkmoths that serve as pollinators.

	Floral scent composition (biosynthetic pathways) in some night-flowering Silene species. From left to right: S. chlorantha, S. vallesia, S. vulgaris, S. latifolia, S. sericea, S. otites, S. italica, S. nutans, S. succulenta, S. subconica, S. viscosa, S. dichotoma, S. saxifraga

	Floral scent composition (biosynthetic pathways) in some night-flowering Silene species. From left to right: S. alpestris, S. armeria, S. rupestris, S. viscaria, S. coeli-rosa, S. gallica, S. dioica, S. pendula, S. flos-cucli, S. flos-jovis

Methods we use in our department:

• Dynamic headspace with solvent extraction of tenax/carbotrap tubes (Aceton)
• SPME (Solid Phase Micro Extraction)
• ChromatoprobeTechnique (for the investigation of pollen odors)
• MicroSPE is a dynamic headspace method followed by thermo desorption (for short interval analysis (~ 2min) of odor changes and odor production in single flowers)

Varian's ChromatoProbe Sample Introduction Device http://www.varianinc.com

Analysis software:

• NIST 2002 database (~174,000 masspectra).
• Mass Spec Calculator Pro for structural fragmentation of drawn structures.
• MassFinder Software for the identification of monoterpenes and sesquiterpenes
• Varians Saturn2000 software for quantification and data analysis (MS/MS)

Actual projects in our department that are related with floral scent analysis

• Floral odors in day-flowering and nigth-flowering Caryophylloideae (Silene, Dianthus)

Biochemical Systematics and Ecology 30 (2002) 383–397. "Flower scent composition in night-flowering Silene species (Caryophyllaceae)."

Biochemical Systematics and Ecology 31 (2003) 345–357. "Flower scent composition in Dianthus and Saponaria species (Caryophyllaceae) and its relevance for pollination biology and taxonomy."

Biochemical Systematics and Ecology 32 (2004) 841–859. "Flower scent composition in diurnal Silene species (Caryophyllaceae): phylogenetic: constraints or adaption to fower visitors?" 

• "The importance of floral scent for the interaction of Silene latifolia (Caryophyllaceae) with the moth Hadena bicruris (Hadeninae)."

PhD thesis of Stefan Dötterl

• "The role of floral odors in the moth and mosquito adapted plant Silene otites for the attraction of mosquitoes" (starting 2004).
• "Chemical composition of carrion fly flowers, particular Asclepidiaceae" [more...]
• "Pollen odors in Ranunculaceae species" [more...]
• "Floral odors in Annonaceae".

Phytochemistry 55 (2000) 551-558. "Floral scent compounds of Amazonian Annonaceae species pollinated by small beetles and thrips."

• "Short time changes in floral odor production"
• "The differentiation of floral odors from different flower parts from single flowers" [more...]
• "The role of leaf volatiles for the interaction of Macaranga (Euphorbiaceae) species with ants"
• "Floral scent evolution in the genus Conophytum (Aizoaceae) in South Africa" [more...]

South African Journal of Botany 70 (2004) 191-205. "Nectar sugar composition and floral scent compounds of diurnal and nocturnal Conophytum species (Aizoaceae)."

Dahl, A.E., Wassgren, A.-B., Bergström, B., 1990. Floral scents in Hypecoum sect. Hypecoum (Papaveraceae), chemical composition and relevance to taxonomy and mating system. Biochem. Syst. Ecol. 18, 157-168.

Delpino, F., 1868-1875. Ulteriori osservazione sulla dicogamia nel regno vegetale. Milano, pt. I (1868/69), pt. II, Fasc. 1 (1870), Fasc. 2 (1875). Estratto dagli Atti della Soc. Ital. Delle Sci. Nat., Vol. XI u. XII, Milano. 

Faegri, K., van der Pijl, L., 1980. The Principles of Pollination Ecology. Pergamon Press, Oxford. 

Gerlach, G., Schill, R., 1989. Fragrance analysis, an aid to taxonomic relationships of the genus Coryanthes (Orchidaceae). Pl. Syst. Evol. 168, 159-165. 

Gerlach, G., Schill, R., 1991. Composition of orchid scents attracting euglossine bees. Bot. Acta 104, 379-391.

Kite, G., Reynolds, T., Prance, G.T., 1991. Potential pollinator-attracting chemicals from Victoria (Nymphaeaceae). Biochem. Syst. Ecol. 19, 535-539.

Knudsen, J.T., 1994. Floral scent composition in Pyrola rotundifolia complex in Scandinavia and Western Greenland. Nord. J. Bot. 14, 277-282. 

Knudsen, J.T., Mori, S.A., 1996. Floral scents and pollination in Neotropical Lecythidaceae. Biotropica 28, 42-60.

Knudsen, J.T., Tollsten, L., 1993. Trends in floral scent chemistry in pollination syndromes: floral scent composition in moth-pollinated taxa. Bot. J. Linn. Soc. 113, 263-284. 

Knudsen, J.T., Tollsten, L., Bergström, G., 1993. Floral scents - a checklist of volatile compounds isolated by head-space techniques. Phytochemistry 33, 253-280.

Knuth, P. ,1898-1905. Handbuch der Blütenbiologie, I Bd. 1898 (Einleitung und Literatur). II Bd. 1898 (Die bisher in Europa und im arktischen Gebiet gemachten blütenbiologischen Beobachtungen. 1. Ranunculaceae bis Compositae, 2. Lobeliaceae bis Gnetaceae, 1899); III Bd. (Die bisher in außereuropäischen Gebieten gemachten blütenbiologischen Beobachtungen. 1.  Cycadaceae bis Cornaceae, 1904, 2. Clethraceae bis Compositae. Nachträge, Rückblick, 1905). Engelmann Verlag, Leipzig. 

Kugler, H., 1970. Einführung in die Blütenökologie. Gustav Fischer Verlag, Stuttgart. 

Vogel, S., 1954. Blütenbiologische Typen als Elemente der Sippengliederung dargestellt anhand der Flora Südafrikas. Botanische Studien Heft 1. Gustav Fischer Verlag, Jena. 

_{Andreas Jürgens}