Pelargonium graveolens or Pelargonium x asperum

The Pelargonium Issue: A rose pelargonium by any other name would smell just as sweet!

Written by Jade Shutes

I recently submitted our Geranium monograph to be printed in a new journal called: The International Journal of Professional Holistic Aromatherapy. This journal is being created by Lora Cantele, past president of the Alliance of International Aromatherapists. The IJPHA is a peer-reviewed professional journal dedicated to providing invaluable information and resources to professional aromatherapists and other healthcare providers. The IJPHA will be provided as a print journal.

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Whilst my Geranium Monograph was being reviewed two comments came in, one was easy to answer, one drove me to research and research and research some more.

The first question:  How many species are there?

This seems to be a debatable answer and instead of having an exact number of species which seems to be unknown, a better and more accurate answer is approximate: e.g. there are over 250 species.

The Second question:  It has been said that the Geranium in todays market comes from Pelargonium x asperum, should we change the name? I had listed Pelargonium graveolens.

In searching for the answer to this question, lets explore the history of Pelargonium species.

HISTORY:  The family Geraniaceae contains three genera: Geranium, Erodium, and Pelargonium. The names, derived from the three Greek words meaning crane, heron, and stork, refer to the resemblance of the seed case to the slender bills of these three birds.  (Arnoldia, 1974)

Pelargonium species originate in South Africa and different species are found in distinct habitats. The Pelargonium species related to the Geranium oil-producing cultivars are mainly located in the Cape area. (Lis-Balchin, 2002)

According to Arnoldia, 1974: The first record of a pelargonium cultivation appeared in England in 1633. In his edition of Gerarde’s “Herbal…”, Thomas Johnson noted that Tradescant (http://en.wikipedia.org/wiki/John_Tradescant_the_elder) had flowered “Geranium indicum nocte odoratum” the preceding year. It is believed that Tradescant obtained his specimen of pelargonium from Cape Town, South Africa. (His specimen was thought to be Pelargonium triste)

Pelargonium triste

It was 1686 when ten pelargoniums species were found growing in the Botanic Garden at Leyden and from this time forward pelargoniums were to be important members of the European garden flora, having been transplanted from South Africa.

Between 1771 and 1772, Francis Masson was sent out from Kew to South Africa where he spent 5-6 years collecting various species of scented pelargonium. He sent back rose scented Pelargonium radens, Pelargonium quercifolium, and Pelargonium graveolens as well as the lemon-scented Pelargonium crispum.  He may also have brought over the peppermint scented geranium Pelargonium tomentosum which appeared in England sometime before 1790.

The issue with clarifying species for Pelargonium arises due to the ease with which the plants hybridize. Once a collection of species has been gotten together, and the bees allowed to go about their business, the resultant seed will yield a myriad of hybrid forms. This is what happened in the gardens and conservatories of Europe between 1750 and 1850. A multiplicity of forms appeared. (Arnoldia, 1974)

Is it a Geranium or Pelargonium:

In 1753, Linnaeus published his Species Plantarum which although it established the binomial system of naming, did not recognize Pelargonium as a distinct genus and retained the generic name Geranium for the 20 Pelargonium species known at that time as well as those known today as Erodium and Geranium. Such was the stature of Linnaeus at the time, that the name Geranium was retained for another 40 years before the name Pelargonium was finally approved. (Miller, D. 2002)

Further confusion within Pelargonium species:

Between 1787 and 1838 seven monographic works were published in an attempt to keep up with the bewildering hordes of seedling pelargoniums. Different names were applied by different authors to the same plant, and identical names were applied by different authors to different plants. Hybrid seedlings were grown under the same names as their maternal parents. the resultant confusion still persists. For example: in some cases the plant which is called Pelargonium ‘Attar of Roses’ seems to be, instead, the old species Pelargonium capitatum; while the plant which is grown as Pelargonium capitatum is really a hybrid between Pelargonium graveolens and Pelargonium radens which is properly called Pelargonium X asperum. Likewise, at least some plants grown as Pelargonium odoratissimum are probably hybrid seedlings of the species with Pelargonium exstipulatum and should be properly called Pelargonium X fragrans.

Based upon genetic work of the genus, M.G. Daker concluded that the majority of aromatic pelargoniums are derived from two species, Pelargonium crispum and Pelargonium graveolens. ( (Arnoldia, 1974)

 

Modern Classification of Pelargonium species

It was 1820 when Sweet  published the first of his five volumes on the Geraniaceae family. Expanding on Sweets work, de Candolle  in 1824, designed his classifications in sections rather then genera (as Sweet did). And then in 1860, Harvey in Florca capensis separated the genus into 15 sections, many of which were combinations of those proposed by Sweet and de Candolle. (Miller, D, 2002)

According to Miller, the most recent classification, which is based upon molecular work and chromosome size, there is a Subgenus species called: Pelargonium. This subgenus species includes the Section Pelargonium. And it is here that we find the Scented geraniums used for oil production. Although several species are listed in this category, only four have been used for essential oil production. These species include:

Pelargonium capitatum (L) L’Heritier.
This species is found in many areas along the coasts of South Africa and is believed to have been amongst the earliest scented geraniums brought to England from Holland in 1690. The true species is quite rare in gardens but is represented by the cultivar ‘Attar of Roses’ with a more upright habit and rougher but strongly aromatic foliage and pinker flowers.  You can order the seeds for this from: http://www.horizonherbs.com/product.asp?specific=2688

Pelargonium capitatum

Pelargonium graveolens L’Hér. ex Aiton
Is a species found wild in the northern part of South Africa, has white flowers and deeply divided, softly hairy, somewhat peppermint-rose scented leaves.

Pelargonium graveolens (from Wikipedia)

Pelargonium radens
This species comes from south-western Cape Province to Transkei and was first introduced to Kew by Masson in 1774. It is not common in cultivation but is considered to be one of the ‘parents’ to the Rose cultivar (also known as Geranium bourbon).

Pelargonium radens (http://www.plantzafrica.com/plantnop/pelargradens.htm)

And under section Peristera, subsection Reniformia is: P. odortissimum (L.) L’Heritier
This is an apple-scented geranium which is more low growing then the above Pelargonium species. The plant has white flowers and grows over a large area in the southern and eastern South Africa.

Pelargonium odortissimum

Miller writes that ‘Rose’ cultivar widely grown for the production of rose-scented Geranium oil has been show to be a hybrid between P. capitatum and P. radens (she cites Demarne and van der Walt, 1989). However the name P. x asperum is not mentioned in her writings.

 

PROTAbase Record

According to the Prota (Plant Resources of Tropical Africa), the rose scented geraniums have been categorized as Pelargonium Rosat Group: Cultivar-group

The Prota database also listed the two as synonyms for one another: Pelargonium graveolens L’Hér.: 2n = 88 (octoploid). Synonym: Pelargonium asperum Ehrh. ex Willd.

Protologue
Cultivar-group name proposed in PROSEA 19: Essential-oil plants (1999).

Family
Geraniaceae

Chromosome number
2n = 77 (heptaploid)

Synonyms
Pelargonium asperum auct. non Ehrh. ex Willd., Pelargonium graveolens auct. non L’Hér., Pelargonium roseum auct. non Ehrh.

Vernacular names
Rose-scented pelargonium, Bourbon geranium (En). Géranium rosat (Fr).

Origin and geographic distribution
Pelargonium comprises about 260 species, most originating from coastal South Africa from Namaqualand to Port Elizabeth. Many Pelargonium species are so easy to grow and have become so popular as garden plants that they are now cultivated worldwide.
Nearly all cultivars of Pelargonium grown for their rose-scented essential oil, called geranium oil, arose in Europe from crossings between introductions from South Africa and are therefore of hybrid origin. Commercial cultivation began in the early 19th Century in Grasse, France. Grasse remained the main centre of production until the Second World War. As a result of a change in the economic climate, cultivation there has ceased. The production of Pelargonium Rosat Group became important in Algeria, Morocco and Réunion, using plants from Grasse, but after increasing steadily for some time, production declined. The most important producers of geranium oil are currently China, Egypt, Morocco and Réunion, but extensive industries of local importance exist in India and the Crimea Peninsula, the Caucasus and Tajikistan.

END PROTA information

 

Geranium essential oil production (Arnoldia, 1970)

Although they had been cultivated for their scent in Europe for more than a century, it was not until 1819 that the aromatic pelargoniums came to the attention of the perfume industry. They were first commercially grown in fields at the foot of the Maritime Alps near Cannes (Knuth 1921). By 1847 they were in regular cultivation both in Grasse, France and in several locations in the French Province of Algeria. In 1880 plantations were established on the French island of Reunion 500 miles east of Madagascar in the Indian Ocean at altitudes between 400 and 1200 meters where sugar cane, vanilla and manioc could not be grown (Perrot 1915).

Just which pelargoniums are now used, or have been used, for commercial oil production is conjectural, since most of the literature seems to have been produced by people not in a position to accurately identify the plants. It is certain that P. X asperum was the major crop in France before 1900. (Revue Horticole, 1893). It is also certain the P. graveolens was the plant grown in Kenya in the 1920’s and 1930’s (Hutchinson 1931). What other species or hybrids may be involved must wait until a taxonomist has an opportunity to study the plants.

It is surprising in view of the diversity of odor presented in the previous table that only those pelargoniums with rose scent are used. Holmes (1913) noted this as well, and proposed that others should be considered. The exclusive use of rose-scented pelargoniums is probably due to the extreme popularity and expense of the rose extract from Damascus roses, for which rose geranium oil was a cheap and acceptable substitute. For other scents, the pelargonium counterpart was probably not outstandingly less expensive. (Arnoldia, 1974)

And finally, according to a 2009 Rose Geranium production manual compiled by Directorate Plant Production in collaboration with members of SAEOPA and KARWIL Consultancy  (Obtainable from Resource Centre Directorate Agricultural Information Services Private Bag X144, Pretoria, 0001 South Africa):

Pelargonium cv. rosé, commonly called rose geranium, is a hybrid species that was developed from crossing P. capitatum with P. radens. The resultant hybrid was then introduced as a farming crop for the production of essential oil. The earliest plantings were made at Reunion Island and the ISO standard, i.e. Bourbon oil with the citronellol/geraniol ratio of close to 1:1, for the oil quality was developed. The essential oil was produced, and named ‘Bourbon’, after the previous name of the island. Reunion was formerly the main producer of this type of oil.
Several rose scented cultivars exist. Pelargonium cv. rosé which yields Bourbon type oil has been the most preferred type. Some others cultivated, are P. capitatum, P. graveolens, and P. graveolens hybrids such as the rose scented Chinese and Algerian varieties. India has developed rose scented cultivars of which K 99 and Kelkar (Egyptian) are best known. Other rose scented cultivars have been developed in Russia.
In Morocco, the Algerian or Tunisian type is the most planted cultivar. Some other cultivar hybrids were made as well in which P. graveolens was used. Egyptian, Chinese, Moroccan and Indian stock has much of this type. The essential oil chemo-types produced by these countries are, however, not close to the preferred Bourbon type. (Note that there is great confusion in the taxonomy between different countries, and hybrids were grown while other varieties are still studied. Linn, ‘Herit’.) Several countries are experimenting and developing new strains.

Lis-Balchin (2002) shares that the main source of the commercial oil is from a cultivar known as P. cv. ‘rose’ giving the ‘Geranium oil, Bourbon’ from Reunion and also lately from China. The ‘Rose’ cultivar has been found to be, most probably, a hybrid between P. capitatum  P. radens.(citing Demarne and van der Walt, 1989).

She also writes that: The International Organisation for Standardization or ISO, defines Geranium oil as
‘The oil obtained by steam distillation of the fresh or slightly withered herbaceous parts of Pelargonium graveolens L’Heritier ex Aiton, Pelargonium roseum Willdenow and other undefined hybrids which have given rise to differing ecotypes in the various geographical areas’ (International standard 4731: 1972). The colour is various shades of amberyellow to greenish-yellow. The odour is given as characteristic of the origin, rose-like with a varying minty note.

 

The present source (Lis-Balchin 2002)

Numerous parts of the world have produced Geranium oil in the past (Weiss, 1997) but even in the country of origin of Pelargonium i.e. South Africa, this has proven to be noneconomical.

Small amounts, for own country consumption is produced in India, Morocco and Algeria. In Kenya it is known as Mawah oil, and is stated to be from P. fischeri (Weiss, 1997). Nowadays, there is no production of Geranium oil in Grasse, which simply acts as a market base for imported oil from all over the world and where some adjustments are made to the oil, demanded for its various uses. African Geranium oil usually refers to the Egyptian oil but also to that of Morocco and Algeria where the same or similar Pelargonium cultivar is used.

China produced a type of Bourbon oil, but Weiss (1997) refers to it as an Morocco-style oil, which makes it more like the Egyptian type. The area of Yunnan, Binchuan, Shiping and Yuxi Provinces are gradually being decreased in favour of other essential oil crops. The descriptions of the unique but different odour qualities found in the essential oil ‘bible’ by Arctander (1960) probably no longer apply to the modern produce. The different chemical compositions of Geranium oils from different geographical areas (Lawrence, 1992, 1994; Weiss, 1997) are also not found to conform to norm in practice, as adulteration of commercial oils is profuse (Lis-Balchin et al., 1996).

ISO 4731 has set the concentration for citronellol content at a minimum 42 percent/maximum 55 per cent for Bourbon Geranium oil; 35/58 for Moroccan; 40/58 for Egyptian and 40/58 per cent for Chinese oils .

 

CONCLUSION

I am still a little unsure of what we are actually getting when we order Geranium or Rose Geranium. Most likely it is the Pelargonium cv. rosé but it could very well be Pelargonium graveolens (or a hybrid thereof) which according to the Kew Gardens P. graveolens L’Herit. is considered a synonym for Pelargonium asperum Ehrh. ex Willd. (also commonly noted as P. x asperum) according to Kew Gardens. (http://apps.kew.org/efloras/namedetail.do?flora=fz&taxon=1180&nameid=2874).  Regardless, it appears that the Rose scented geranium has great interest and is considered to be the most desirable.

To read the Geranium Monograph, be sure to subscribe to the International Journal of Holistic Professional Aromatherapy. Email Lora Cantele at: enhancements@ameritech.net

 

While researching this article I found it interesting to note the entries for both P. asperum and P. graveolens in Pubmed and Science Direct.

PUBMED
2 listings under P. asperum
1 listing under P. x asperum
31 listings under P. graveolens

ScienceDirect
29 listings under P. asperum
22 listings under P. x asperum
343 listings under P. graveolens

 

I also came across some interesting information on Geranium species:

Rose Geranium Patents
While researching this article I found two interesting Patents for Rose Geranium essential oil.  See these Geranium patentUSPP20149.

And even more interesting and perhaps a bit nerve wracking: Transgenic Geranium

 

REFERENCES

Arnoldia, No authors given. Aromatic Pelargoniums Arnoldia, 1974. Volume 34 Number 3 – May 1974.   arnoldia.arboretum.harvard.edu/pdf/…/1974-34-3-aromatic-pelargoniums. pdf)

http://www.plantzafrica.com/plantnop/pelargtrist.htm

Lis-Balchin M., Editor. (2002) Geranium and Pelargonium: The genera Geranium and Pelargonium. London: Taylor and Francis.

Miller, D. (2002) The Taxonomy of Pelargonium species and cultivars, their origins and growth in the wild. Geranium and Pelargonium: The genera Geranium and Pelargonium. Lis-Balchin M., Editor.  London: Taylor and Francis.

Prota Database retrieved on April 18, 2012 from: http://database.prota.org/PROTAhtml/Pelargonium%20Rosat%20Group_En.htm

Cited by Lis-Balchin (2002)

Demarne, F. and van der Walt, J.J.A. (1989) Origin of the rose-scented Pelargonium grown on
Reunion Island, S. Afr. J. Bot., 55, 184–191.

Arctander, S. (1960) Perfume and Flavor Materials of Natural Origins, Elisabeth, New Jersey.

And many others which can be found in the book “Geranium and Pelargonium: the genera Geranium and Pelargonium”.