The Basis of Scents
WHY DO ROSE GERANIUMS SMELL LIKE THAT?
By Wayne L. Handlos, Ph.D.
We have learned that rose geraniums produce some essential oils that make them useful
for aromatherapy. The article "Trichomes" contains information and images of the hairs on the surface
of geranium plants. These hairs produce the essential oils that give the geraniums their distinctive odors.
But what are the chemical compounds that that are found in these essential oils? Rose scented Pelargonium
At the risk of going overboard biochemically, the primary constituents of the essential oils of
the rose scented geranium (Pelargonium cv Rosé) are listed in the table on the next page.
Many studies and analyses have been done on geraniums (as well as many other plants) to
identify the compounds that they contain. (These studies are done for a variety of scientific
reasons relating to the study of plant evolution, relationships between plants and insects,
search for new medicines and physiological agents, search for insect attractants and pesticides,
elucidating metabolic pathways, etc.) Because rose geranium oil is such an important
ingredient for the “scent industry” (it has many of the same characteristics and constituents
of rose oil and is much cheaper to produce) there are many studies available.
The composition of the oil varies depending on the country of origin, stage of growth, season,
nutrition of the plants and probably other factors.
Rose geranium oil from Egypt wholesales for $884 per gallon. Damask rose oil from Bulgaria
costs £37.11 for 10 ml (2 tsp) while Zambian rose oil is £51.30 for 10 ml. On the other
hand, geranium oil varies from £4.87 to £8.78 (for Bourbon oil from Reunion) for 10 ml.
COMPONENT % FRAGRANCE PARTS IN SYNTHETIC GERANIUM OIL
Cis-rose oxide 0.2 fruity, rose, sweet 150
Menthone 0.4 minty 150
Isomenthone 7.8 clean mint 500
^ geraniol Citronellol 19.0 floral, fresh, rosy 2800
Geraniol 21.5 sweet, rose-like 1500
Citronellyl formate 8.5 strong, fruity, rose-like 1000
Geranyl formate 9.5 fruity, floral, rose 800
Beta-caryophyllene 0.8 cinnamon, clove, spicy ...
Guaia-6-9-diene 7.2 ...... 500
^ citronellol Geranyl propionate 1.6 floral, rose, lemon 150
Germacrene D 2.1 woody, earthy, spicy ...
Citronellyl butyrate 1.1 floral, fruity, rose ...
Geranyl butyrate 1.2 fruity, rose, apple ...
Phenylethyl tiglate 0.7 green, raspberry, strawberry, rose ...
^ isomenthone Geranyl tiglate 1.4 floral, geranium 150