Oleum Palmarosae seu Geranii Indicum. - Oil of East Indian Geranium. - Essence de Geranium des Indes. - Palmarosabl.
Origin. Palmarosa oil, also known as Indian grass oil, rusa oil, Indian or Turkish geranium oil3), is distilled from the over-ground portions of the rusa or geranium grass designated as Cymbopogon Martini, Stapf4). The numerous synonyms of this herb are: Cymbopogon Martinianus, Schult., Andropogon Martini, Roxb., A. pachnodes, Trin., A. Calamus aromaticus, Royle, A. nardoides, a, Nees, A. Schoenanthus, Fluck. et Hanb., non L, A. Schoenanthus var. genuinus, Hack., A. Schoenanthus var. Martini, Hook. f. The popular designation rusa, applied to this grass, is probably traceable to the reddish-brown color taken on by the panicles in fall.
1) Dymock, Warden and Hooper, Pharmacographia indica. Part IV, p. 535.
2) Pharmaceutical Journ. III. 10 (1880), 635.
3) The erroneous designation "Turkish geranium oil", which has practically been abandoned, dates back to a time when the oil entered the European market via Constantinople. From Bombay it was transported by ships to the ports of the Red Sea and thence by overland routes through Arabia to Constantinople. After having been specially prepared it was here used on a large scale to adulterate rose oil. (See also p. 189).
4) Kew Bull. 1906, 335.
Cymbopogon Martini occurs in two varieties which are known in India as motia and sofia. According to Stapfl) they cannot be differentiated morphologically when dried specimens are compared. ). H. Burkill2), however, states that in the fields they can be distinguished by their different habits. The greatest difference between these two varieties becomes apparent in the composition of their volatile oils. The motia (= pearl, precious) yields the palmarosa oil, and the sofia (= mediocre) the ginger-grass oil. Burkill regards this difference as sufficient justification to designate the two varieties as Cymbopogon Martini var. motia, and C M. var. sofia.
With the exception of the deserts and steppes of the Punjab, the outer slopes of the West Ghat and apparently a large portion of North Karnatik, the rusagrass, according to Stapf, grows from the Rajmahal mountains (at the turn of the Ganges) up to the Afghanistan border and from the subtropical zone of the Himalaya to the twelth degree of latitude.
According to Forsyth, the grass begins to bud about the latter part of August and flowers to the end of October. The distillation must be conducted during this season, more particularly during the early flowering period, since the yield suffers an appreciable diminution later and its quality likewise depreciates.
So far as the conditions favorable to their vegatation are concerned, Burkill has found that the motia thrives best on dry ground, either at the foot of the hills or at moderate altitudes on the southern slopes but moderately covered with trees. The sofia, however, demands moisture and grows preferably where this is supplied by abundant dew and fog. It prefers higher altitudes up to the tops of the hills, but is also found on the lower slopes, however, not on those with southern exposure. Its favorite haunts are the teak forests (Tectona grandis, L or East Indian oak), in which the rapid evaporation at night causes a decided reduction in the temperature of the atmosphere and hence abundant formation of dew. However, it should be stated that both motia and sofia may occur at any altitude, provided the other conditions are favorable.
1) Report of Schimmel & Co., April 1907, 58.
2) J. H. Burkill, First notes on Cymbopogon Martini, Stapf. Journal of the Asiatic Society of Bengal, March 1909, Vol. V, No. 3 (N. S.); Report of Schimmel & Co., October 1909, 90.
So far as the regional distribution of the two grasses is concerned, Burkill ascertained that indeed motia and sofia occurred side by side at different altitudes near Asirgarh, Chandni and in the Melghat region. However, in Deogaon and Belkhera, to the west and northwest of Ellichpur, an important commercial center for palmarosa oil, also in Dhamangaon motia occurs almost exclusively. Further up in the mountains he found more sofia. Beyond the watershed in the Sipna valley as far as Tapti he found sofia exclusively.
The differences between motia and sofia vary with the region, according to the more favorable conditions found by the one or the other variety. Hence the statements made by collectors vary accordingly. Thus, on the one hand, in the vicinity of Asirgarh and Chandni motia is more erect and attains a height of from 6 to 8 feet, whereas sofia is but 3 to 4 ft. high and produces dense bushy ears. On the other hand, in the Melghat region, sofia is the higher plant. The width of the leaves and the intensity of the color increase with the height. As opposed to motia, the sofia is characterized by the large number of radical leaves. The sofia leaves also form a different angle with the sheath than do the motia leaves. Of further interest is Burkill's observation that in certain regions grasses occurred that were neither motia nor sofia but which he regarded as cross forms. Until the study being made of C. Martini has been completed, he regards it too early to make a final statement, since, no doubt, other varieties may be found.
Production1). Taking into consideration the wide distribution of this grass, the territory in which it is distilled for its oil is rather limited. In the Bombay presidency, palmarosa oil is distilled principally in the Khandesh district, more particularly in the vicinities of Pimpalner, Akrani, Nandurbar, Shahada and Taloda. In Berar province, the oil is distilled in the districts of Nagpur, Jebalpur, Akola, Buldana, Ellichpur, Basim, Wunn and Amraoti. The city of Ellichpur is the principal market of this province. Oil distilleries are also found in Radschputana, e.g. in Ajmere; furthermore in the British Central Provinces: in the districts of Nimar, Hoshangabad, Betul, Mandla and Seoni. The Nimar district has always been an important center, the oil being designated Nimar oil.
1) Comp. David Hooper, Chemist and Druggist 70 (1907), 207 also G. Watt, The commercial products of India, London 1908, p. 452.