SOME THOUGHTS ON SCENTED GERANIUMS – Part 1 Wayne Handlos
Molecules of Essential Oils
“The scent of geranium leaves is not a subject
for logic, only a cause of delight.”
The Joy of Geraniums
by Helen Van Pelt Wilson.
Scented geraniums/pelargoniums are known for the fragrance of their foliage. The
compounds are generally essential oils – volatile to varying degrees –
produced in the glandular
hairs (trichomes) which clothe the leaves and stems in varying densities.
Most scented geraniums/pelargoniums are in the taxonomic section (§) called
These plants can become shrub-like with woody stems under favorable
conditions. While their
flowers are neither large nor showy, the plants are easy to grow and to
propagate. The species
in this section include:
P. betulinum, P. capitatum, P. citronellum, P. cordifolium, P. crispum, P.
P. denticulatum, P. englerianum, P. glutinosum, P. graveolens, P.
greytonense, P. hermanniifolium,
P. hispidum, P. panduriforme, P. papilionaceum, P. pseudoglutinosum, P.
P. radens, P. ribifolium, P. scabroide, P. scabrum, P. sublignosum, P.
tomentosum, P. vitifolium.
The other group of widely recognized scented geraniums is in section Reniformia
the following species:
P. abrotanifolium, P. album, P. dichondrifolium, P. exstipulatum, P. x
fragrans, P. ionidiflorum,
P. odoratissimum, P. reniforme, P. sidoides.
This is a group of small-leaved, herbaceous or small woody shrubs which are
easy to grow.
Flowers are generally small, borne in open, few-flowered inflorescences.
There are a number of other species with scented leaves
including the following: P. mollicomum,
P. worcesterae, P. x hortorum (zonal
geraniums), P. endlicherianum, P. fulgidum, P.
P. grandicalcaratum among others.
Commercially, geranium oil or rose geranium oil is distilled
(extracted) from the leaves and stems of
"rose geraniums". Over 120 volatile constituents have been
identified in geranium oil. This oil is used cosmetically –
in perfumes, scenting soaps and lotions, etc.
Because of its similar fragrance and lower cost it is used
as a substitute for real "rose oil" or attar of roses.
Geranium oil has been produced in a variety of locations
over the years including
Reunion, China, Egypt, India, Morocco, Algeria, Kenya,
France, Corsica, Tunisia, Congo, Tanzania, Madagascar,
South Africa, Spain, Portugal and Brazil. It takes about
300-350 kg of plant material (leaves and stems) to produce
0.3 to 0.7 kg of oil. On a per hectare basis a very
productive field can be expected to produce about 45 kg of oil
There are several different cultivars used in the production
of geranium oil. The better-known ones include: ‘Rosé’,
or cultivars named for the country of origin (Algerian,
Tunisian, Bourbon, Reunion, Egyptian), or a new one from tissue
culture called ‘Narmada’. The following list shows some of
the primary constituents of the fragrances produced by
different species and cultivars. [Most information is from M. Lis-Balchin,
2002, Geranium and Pelargonium. The letter "L"
indicates results from J.Y.Y.
Lalli’s dissertation on
essential oils in Pelargonium spp.]
P. capitatum – α pinene, myrcene, citronellol,
citronellyl formate, geranyl formate, β caryophyllene, guaia-6-9diene,
another analysis – L viridiflorol - 24-36.6%; another
selection – citronellyl formate (37.1%), citronellol (9.9%),
furopelargone B (6.1%)
‘Attar of Roses’ – linalool, isomenthone, citronellol,
geraniol, citronyllyl formate, guaia-6-9-diene
‘Rosie’ – isomenthone, citronellol, geraniol, citronellyl
formate, geranyl formate, guaia-6-9-diene
P. radens – isomenthone, citronellol; another analysis –
L isomenthone (84.5%)
P. graveolens – linalool, isomenthone, citronellol,
geraniol, citronellyl formate; another – L isomenthone (65.8%, 83.3%)
‘Rober’s Lemon Rose’ – linalool, isomethone, citronellol,
geraniol, citronellyl formate, β caryophyllene
P. tomentosum – menthone, isomenthone; another analysis
- L menthone (36.1-41.1%), isomenthone (49.356.6%)
‘Chocolate Tomentosum’ – α phellandrene, menthone,
‘Lady Plymouth’ – isomenthone
P. vitifolium – citronellol, citronellic acid; another
analysis – L citronellic acid (74.4%)
P. papilionaceum – citronellic acid, geranic acid;
another analysis – L citronellic acid (96.2%)
P. citronellum – citronellol, geranial; another analysis
– L geranic acid (36%), neral (17.4%), geranial (27.2%)
P. crispum variegatum –
citronellol, geranial and other sesquiterpenes
P. scabrum – terpinen -4-ol, citronellol, geranial, (other sesquiterpenes); (L 14 hydroxy β
‘Lemon Fancy’ – neral, geranial (and other sesquiterpenes)
P. glutinosum – α phellandrene, p-cymene, limonene,
hexanyl butyrate, sesquiterpenes (L caryophyllene (6.3%), spathulenol
P. x fragrans – α pinene, limonene, fenchone, methyl
P. odoratissimum – fenchone, isomenthone, piperitone,
P. exstipulatum – α thujene, α pinene, limonene, other
P. quercifolium – β pinene, α terpineol (L p-cymene
(54.9%), viridiflorol (13%), spathulanol (5.9%); another selection –
‘Clorinda’ – β pinene, α phellandrene
‘Copthorne’ – α thujene, β pinene, fenchone, β caryophyllene
‘Village Hill Oak’ – p-cymene, terpine-4-ol, neral/citronellol
‘Sweet Mimosa’ – α-thujene, β pinene/myrcene, isomenthone
P. grossularioides – fenchone, isomenthone, citronellal,
geraniol, methyl eugenol
P. filicifolium – p-cymene-8-ol
P. panduriforme – L p-cymene (37.6-45.4%)
P. hispidum – L decanoic acid (47%), 2-decanoic acid
P. cucullatum – octyl acetate P. betulinum – L T
N. Oyama-Okubo. 2010, Bull. Natl. Inst. Flor. Sci. 10:55-63
- Rose – β-guaiene (22.4%), β-citronellol (13.5%), citronellyl formate
- ‘Lady Plymouth’ – citronellyl formate (22.6%), β-citronellol (20.7%),
- ‘Dr. Livingston’ – β-citronellol (28.4%), iso-menthone (24.7%),
- ‘Skeleton’s Unique’ (P. radens) – β-guaiene (42.0%), β-caryophyllene
(9.2%), geranyl acetate (8.5%)
- ‘Snowflake’ – β-guaiene (44.1%), β-citronellol (11.9%), β-caryophyllene
- ‘Peppermint’ (P. tomentosum) – isomenthone (49.5%), menthone
(34.0%), β-caryophyllene (7%)
- ‘Chocolate Peppermint’ – isomenthone (14.8%), menthone (25%), β-caryophyllene
- ‘Lemon’ (P. crispum) – geranial (α-citral) (38.9%), neral (β-citral)
(27.2%), β-guaiene (13.5%)
‘Clorinda’ – β-guaiene (15.7%), aromadendrene (13.2%), β-caryophyllene
‘Mrs. Kingsley’ – β-guaiene (41.9%), germacrene D (7.5%)
‘Sweet Mimosa’ – isomenthone (24.3%), germacrene D (9.7%)
B. Bozan et al. 1999. Pl. Med. 65:781-782 [Essential oils in
flowers of P. endlicherianum] (91% of the essential oils consist of
compounds including the following: germacrene D (16%), β-caryophyllene (6%), α-zingiberene
(3.2%), 2-phenylethyl 2 methyl
butyrate (12.5%), T-cadinol (4.7%), tricosane
F.S. Sharopov et al. 2014 [P. graveolens grown in Tajikistan]
produce 95.1% of the essential oils including the following: citronellol (37.5%), geraniol (6%), caryophyllene oxide (3.7%),
menthone (3.1%), linalool (3%), β-bourbonene
(2.7%), isomenthone (2.1%), geranyl formate (2%)).
J.A. Pino et al. 2001. [Analysis of Rose geranium oil
produced in Cuba] (54 compounds produce 95.5% of the essential oil
including citronellol (25.6%), αguaiene (7.2%),caryophyllene oxide (14.7%)).
F.E. Demarne and v.d.Walt. 1992. [Essential oils of
P. vitifolium with the following composition: citronellic acid (77-85%),
F.E. Demarne. 1993. [Essential oils in four natural
populations of P. citronellum in South Africa with the following
predominant: neral (27-37%), geranial (36-48%)]
A.M. Viljoen. 1995. [Essential oil analysis of 40
populations of P. capitatum in South Africa showed high levels of
essential oil variation, consisting of 18 chemotypes.]
Characteristics of some of the primary essential oils
have been described in "Why do those geraniums
smell like that?", "Why do rose geraniums smell that
way?", "Trichomes" and others.
Here are ten more compounds.
Aromadendrene – sesquiterpene, with a woody fragrance, found
in Eucalyptus and P. endlicherianum.
Beta guaiene – sesquiterpene, with a sweet, woody, earthy or
spicy odor; found in sweet flag oil.
Germacrene D – sesquiterpene with a woody, spicy fragrance;
exhibits antimicrobial and insecticidal properties;
found in feverfew, tansy and yarrow leaves and pine needles.
Linalool – terpene alcohol found in coriander, orange,
lavender and basil; floral spicy fragrance; insecticide for fleas,
fruit flies, cockroaches; synthesized from geraniol, myrcene,
Myrcene – monoterpene found in thyme, cannabis, hops, lemon
grass; pleasant odor (earthy to clove like to pungent
depending on concentration; from geraniol.
Octyl acetate – ester found in frankincense oil and
Heracleum candolleanum rhizome, with a fruity, earthy, herbal or
Piperitone – monoterpene found in Cymbopogon, Mentha
(mint); peppermint, herbal, minty or camphor scent.
Spathulenol – tricyclic sesquiterpene found in Artemisia;
earthy fragrance; repellant to some ants.
T-cadinol – sesquiterpenoid alcohol found in myrrh (Commiphora
sp.), basil oil, pepper tree leaves, pine needles with
a balsamic or earthy fragrance; antifungal properties.
Viridiflorol – tricyclic sesquiterpene; herbal, sweet,
fruity, or minty odor.
Factors affecting essential oil production – The composition
of geranium oil is variable. This variability is due to the
relative concentrations of the various compounds found in
the oil. In the case of commercial rose geranium oil this variation
is related to eight compounds: E and Z rose oxides,
linalool, geraniol, citronellal, isomenthone, guaia-6-9-diene and
10-epi-γ-eudesmol. The composition of geranium oil is due to
differences in cultivars, the climate (sunlight, rainfall,
temperature), time of harvest (the season), fertilization.
Variation is also affected by soil, plant part, crop age, fertilization,
presence of weeds/disease, shade, irrigation, temperature,
humidity, rainfall and time of harvest. For example, in hotter
months more citronellol is produced while in cooler months
more geraniol is produced. Thus the oil produced in cooler months
would smell more citrusy, but in the warmer months the oil
would smell more rosy.
Functions and effects of geranium oil – Geranium oil exhibits
anti-microbial and anti-fungal properties. There are degrees
of anti-bacterial action by oils from different locations.