Rosa alba L. - Rosaceae - white rose (of York), **Weiße Rose**, Alba-Rose

Shrub, up to 2m tall, only known in cultivation (old garden rose of the Greeks and Romans); prickles irregularly set on the stems, usually hooked and uniform; leaves with 5-7 leaflets, ovate to broadly elliptic, obtuse, simply serrate, glabrous above, paler, grey-green, ± hairy beneath; flowers solitary or 3(-5) rarely more, white or rarely pale pink, simple or usually double or semidouble, rarely simple, fragrant. \\
[[http://www.efloras.org/florataxon.aspx?flora_id=5&taxon_id=242345219]]

"... the classical European rose gardens were totally dominated until the beginning of the 19th century by the old famous fragrance roses Rosa alba, [[rosa_gallica_l|R.gallica]], [[rosa_centifolia|R.centifolia]], and [[rosa_x_damascena|R.damascena]]..." \\
The scent of Rosa alba is based on citronellol (6.8%), nerol (10.2%), geraniol (17.0%), and 2-phenylethyl alcohol (16.9%). Further components are caryophyllene (23.0%), geranyl acetate (4.5%), α-pinene (3.0%), benzyl alcohol (2.5%), citronellyl acetate (0.4%), geranial (0.4%), neral (0.3%), cis-rose oxide (0.05%), trans-rose oxide (0.05%) eg. \\
[Meaningful Scents around the World, Roman Kaiser, Zürich 2006, 156-157, 253] 

The essential oil of white oil-bearing roses (R. alba L.) from Bulgaria contained 214 compounds (GC-MS). The major part of the oil components were hydrocarbons like heneicosane (17.4%), nonadecane (15.0%), nonadecene (6.7%), tricosane (4.6%), pentacosane (1.4%) and heptacosane (1.6%). Major other components were citronellol (13.3%), geraniol (9.0%), nerol (4.3%), caryophyllene (3.0%), and farnesol (2.3%). \\
[Bulgarian rose oil of white oil-bearing rose., Nedkov, N., Dobreva, A., Kovacheva, N., Bardarov, V., Velcheva, A., Bulg J Agric Sci, 15, 2009, 318-322] [[http://www.agrojournal.org/15/04-07-09.pdf]]

In opening phase 4 (the flower is semi-opened, to see the stamens) oil content of Rosa alba flowers peaked at 0.028%. In phase 5 (flower is completely opened, the stamens are yellow) oil content was 0.020%. \\
The composition of the essential oil of the flowers of Rosa alba L. changed during flower opening. Whereas nonadecane (21-26%) and heneicosane (19-21%) dominated in phase 2 and 3 of flower developement, citronellol+nerol (21-22%) and geraniol (23-28%) were the main volatiles in stages 4 and 5. At this times, further components were ethanol (0.01-0.04%), linalool (1.6-2.0%), cis-rose oxide (0.02-0.04%), trans-rose oxide (0.03%), phenylethanol (0.02%), geranial (0.1-0.4%), β-damascenone (0.02-0.06%), β-caryophyllene (1.7-2.0%), geranyl acetate (0.3%), eugenol (0.3%), methyl eugenol (0.7%), heptadecane (5.1-5.6%), nonadecane (9.2-10.9%), eicosane (1.3-1.5%), heneicosane (9.5-11.0%), and tricosane (1.7-2.1%). \\
[Dobreva, A., & Gerdzhikova, M. (2013). Content and composition of the essential oil of Rosa alba L. during flower development. Agricultural Science & Technology (1313-8820), 5(1).] [[http://tru.uni-sz.bg/ascitech/1_2013/019%20Content%20and%20composition%20of%20the%20essential%20oil%20of%20Rosa%20alba%20L.%20during%20flower%20development.pdf]]

{{:rosa_alba.jpg?600}} \\
Duhamel du Monceau, H.L., Traité des arbres et arbustes, Nouvelle édition [Nouveau Duhamel], vol.7 t.16, fig. 1 (1819) [P. Bessa] \\
[[http://plantgenera.org/species.php?id_species=1259719]]

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Rosa alba, [[https://creativecommons.org/licenses/by-sa/3.0/de/|CC BY-SA 3.0]], Author: Andreas Kraska