Erysimum cheiri (L.) Crantz - syn.Cheiranthus cheiri L. - Brassicaceae - wallflower, Goldlack

Biennial herb or subshrub, native to Europe, widely cultivated elsewhere as ornamental; basal leaves similar to cauline, cauline leaves obovate to oblanceolate, up to 22cm long, entire; flowers fragrant, orange, yellow, brown, red, purple, violet, or white.
http://www.efloras.org/florataxon.aspx?flora_id=1&taxon_id=250009726

„The top of the stem is occupied by a club-shaped inflorescence of strongly scented flowers. Each flower has purplish-green sepals and rounded petals which are two to three centimeters long and in shades of bright yellows to reds and purples… varieties such as 'Blood Red Covent Garden' are easy to grow and often benefit from being sown and left to their own devices, growing on patches of empty land with little effort required to maintain them, providing aesthetically sound blooms which produce heady scents.“
http://en.wikipedia.org/wiki/Erysimum_cheiri

Cheiranthus cheiri L. was the wallflowers officially and scientifically name, coming from the Arabic, 'kairi' or 'kheyry' as a 'fragrant plant'.
http://www.gaissmayer.de/index/seiten/duftpflanzen/goldlack.htm

The seeds of wallflower contain glucocheiroline, which yields cheirolin (1-isothiocyanato-3-(methylsulfonyl)-propane, also the name of the essential oil of the seeds) on enzymatic cleavage. Cheirolin is obtained from defatted seeds by extraction with dry ethanol.
[Untersuchungen über Senföle; das Cheirolin‐glykosid., Schneider, W., Lohmann, W., Berichte der deutschen chemischen Gesellschaft, Vol.45(3), 1912, 2954-2961]

Application of the vacuum headspace method to the picked flowers (green parts cannot be totally removed) lead to higher amounts of mustard oil compounds in the concentrate. Compounds like 4-methylthio butyronitrile (1-5%) and 3-methylthio propylisothiocyanate (2-30%) originate from enzymatic processes which are started by destruction of plant tissue. Another main constituent of the vacuum headspace concentrate was anthranilic aldehyde.
[Volatile constituents of European bird cherry flowers (Padus avium Mill.). Surburg, H., Güntert, M., Schwarze, B.,Journal of Essential Oil Research, Vol.2(6), 1990, 307-316]

The essential oil of the flowers (0.06%) contained e.g. anisaldehyde, nerol, geraniol, linalool, indole, acetic acid, salicylic acid, anthranilic acid, and methyl anthranilate.
[Azimova SS, Glushenkova AI, VinogradovaVI.Lipids, lipophilic components and essential oils from plant sources. London:Springer-Verlag, 2012, 210]

Rousseau,J.J., La botanique de J.J.Rousseau, t.8 (1805) [P.J.Redouté]
http://plantgenera.org/species.php?id_species=406140

Erysimum cheiri, CC BY-SA 3.0, Author: Andreas Kraska