MOCK-ORANGE
SYRINGA, SWEET MOCK-ORANGE
Philadelphus coronarius
Mock-orange Family [Hydrangeaceae]
6th July 2008, Walkden, Greater Manchester. Photo: © RWD
Flowers profusely. Grows to 20 feet tall.
With four white petals.
17th June 2004, Leek Canal, Cheddleton. Photo: © RWD
Which smell of oranges.
The stems are long and light-coloured, with oppositely paired, broad, slightly toothed leaves.
A profusion of creamy yellow stamens in the centre.
27th June 2005, Castleton, Greater Manchester. Photo: © RWD
A double flowered form, possibly Philadelphus Virginal, has bright green leaves and grows but 6 to 8 feet tall.
A double flowered form, possibly Philadelphus Virginal (Common Mock-Orange).
Easily confused with : 60 other varieties of Mock Orange. Mock-Orange is not orange, the flower are white (apart from Philadelphus coronarius 'Aureus' where the flowers are a golden yellow). It just smells of oranges.
Distinguishing Feature :
No relation to : Oranges [a plant with similar name that just happen to smell similar]
There are up to 60 different varieties of Mock-Orange, and about half a dozen double-flowered forms. All the flowers smell of orange blossom to a greater or lesser degree. Some grow to 20 feet high, as does Philadelphus Coronarius, others to only 10 feet or lower. Most have long arching branches which grow up to 6 feet long in a single season.
Mock-Orange, a flowering shrub, sends out long arching new woody shoots in spring that extend a metre or more. The flowers have four white petals and smell of oranges and of Jasmine . It tends not to flower well if highly pruned. Although deciduous, shedding most of their leaves in autumn, the tips of branches may retain a few leaves over winter. Only a few of the 60 varieties are evergreen.
MOSTLY TERPENOIDS
The essential oil contains volatiles such as two homoterpenes DMNT and TMTT plus 2-AminoBenzaldehyde but with 13-epi- Manool being the major component of the oil obtained from fresh flowers (48%).
2-AminoBenzaldehyde has a sweet spring-flower fragrance which is not only the major constituent in the floral scent of Mock-Orange (at 10%) but also of Robinia pseudoacacia (>20%), Spartium junceum (10-20%) and Pitospermum tobira (at 1-5%). The floral scent of Mock-Orange also contains 46% of the very fragrant trans-Myrtenal and 5% of the related Nopinone. Manool is an aromatic diterpenoid commercially available as a fragrance for use in cosmetics and is used as a pheromone by many insects.
The oils from the fresh leaves contain two main components: 37% (E,E)- Farnesol (2E,6E)-3,7,11-TriMethylDodeca-2,6-Trien-1-ol)) as the major component whereas (E,E)-2,4-DecaDienal at 2.4% is the major component of the oil from fresh twigs.
Farnesol was first found in the Farnese Acacia Tree (Vachellia farnesiana) where it was harvested from the flowers as a perfume. It is also present in the essential oils derived from plants such as cyclamen , lemon grass, ros e, musk, balsam, citronella and neroli. Farnesol is also emitted by the pathogenic fungus Candida albicans which uses it as a quorum sensing molecule to inhibit filament formation at certain population densities. It is the alcohol of Farnesene.
At low concentrations (E,E)-2,4-DecaDienal smells of citrus, orange or grapefruit but at higher concentrations (>10ppm) smells of deep fat fried chicken. (E,E)-2,4-Decadienal is also found in butter, potato crisps and roasted peanuts. The latter compound may be responsible for the smell of oranges possessed of Mock-Orange.
DITERPENOIDS
The oil from the dried flowers contains the diterpenoid IsoLongifoliol at 15% concentration with the sesquiterpenoid 2-Nonanol at 11% which smells of Cucumber and is used by some insects as a pheromone and 8% Umbelliferone (7-HydroxyCoumarin).
IsoLongifolenone
[The Isolongifoliol (aka Isolongifolol) above should not be confused with the similarly named IsoLogifolenone (a totally different natural compound based upon IsoLongifolene which has a similar number of carbon atoms in the skeleton of the rings (11) to IsoLongifoliol but possessing a naphthanene skeleton with two fused 6-membered rings - IsoLongifoliol has only one six-membered ring however it is drawn). The similarity in names perhaps reflects the possibility that in the past when analytical chemistry was not as advanced as it is today the two were once assumed to possess the same skeleton.
IsoLongilolenone occurs in the South American Tauroniro Tree (Humiria balsamifera), and is a another polycyclic sesquiterpenoid. It is used extensively as an ingredient in cosmetics for its ability to repel blood-sucking anthropods which are prone to carry disease. It is more effective at preventing bites from these insects than is the widely used but discredited DEET (N,N-DiEthyl-3-Methyl Benzamide)].
IsoLongifolenone does not, as far as your Author can ascertain, occur in Mock-Orange.
SPIRO-KETALS
Chalcogran is also found in the floral fragrance of Mock-Orange, but is also the principle pheromone used by the Bark Beetle (aka Spruce Engraver) Pityogenes chalcographus. Conophtherin is not found in Mock-Orange but is isomeric (having the same chemical formulae but differing spatial configurations) with Chalcogran, and is also a pheromone.
MONOTERPENOIDS
Trans-Myrtenal is present in the scent of Mock-Orange by as much as 46% with just 2% being cis-Myrtenal together with Nopinone at 5%. (Myrtenal is the aldehyde of Myrtenol which is found in Bog Myrtle but is only present in trace amounts in the scent of Mock-Orange).
Philadelphus coronarius ⇐ Global Aspect ⇒ Hydrangeaceae
(Mock-Oranges)