45. Andropogon citratum, De Cand.—Lemon-Grass.
Although all the Anglo-Indian botanists, whose works I have consulted, consider the Lemon-grass of India to be identical with the Andropogon Schoenanthus of Linnaeus, yet various circumstances have long since led me to suspect that they are in error. Its citron or lemon odour is so very strong and remarkable, that any one familiar with the plant, or its volatile oil, could not overlook or mistake it. Yet not one of the authorities quoted by Linnaeus, nor any of the pharmacologists of the last century who were familiar with the Linnaean plant, mention it. Rumphius, [Herb. Amboinense, pars v. lib. viii. cap. 24, p. 181, tab. lxxii. Fig. 2, Amstel. 1750.] whose figure of the plant is referred to by Linnaeus, says the odour of the Amboyna plant is similar to that of roses mixed with that of new-mown hay. Dale [Pharmacologia, 3tia ed. p. 258, 1737.] describes the odour of Schoenanthus as being sweet and very fragrant, and Lewis [Experimental History of the Materia Medica, 4th ed. vol. ii. p. 20, 1791.] simply says it is agreeable.
The first botanical writer who notices the peculiar citron odour of lemon-grass is De Candolle, [Catalogue Plantarum Horti Botanici Monspeliensis, p. 78, Monspelii, 1813. Link (Hort. Berol, i. 242, 1827), and, following him, Kunth (Enum. Plant, i. 493, 1833), in quoting this work, have substituted the name A. citriodorus for A. citratum: the former name does not occur in De Candolle'a Catalogue.] who states that under the name of Andropogon citratum there was frequently met with in botanical gardens a grass which had very much the habit of A. Schoenanthus, but was larger, did not require a hot house, and was most distinctly characterized by the citron-odour of the bruised leaves. The late eminent botanist professor Th. Fr. L. Nees von Esenbeck [Geiger's Pharmacie, 2te Aufl. by Th. F. L. Nees von Esenbeck, J. H. Dierbach, and C. Marquart, 2te Abth. 1te Hälfte, S. 147. 1839.] pointed out some botanical characters which distinguish the two plants. Thus he states that the leaves of A. citratum, De Cand. are much broader, flat, of a strong bluish-green colour, and both above and at the margin are very rough when drawn backwards through the fingers; whereas, the leaves of A. Schoenanthus are narrow (half a line in breadth), completely keeled, like those of the sedges, bluish-green, and somewhat sharp at the margin when drawn backwards through the fingers. Moreover, the hairs of the rachis of the spikelets of the A. citratum are much shorter than those of A. Schoenanthus.
Lemon-grass is a native of the continent of India and of Ceylon. It was introduced into the West Indies towards the latter part of the last, or beginning of the present century. [Hamilton, Pharmaceutical Journal, vol. vi. p. 369, 1846.]
The peculiar characteristic of this species of Andropogon is its odour, which, when the grass is fresh, is very distinctly citron-like; or rather, especially when the plant is dry, resembles that of balm—the Melissa officinalis, Linn., called by the French Citronnelle.
The lemon-grass yields, by distillation, an essential oil, which is imported from Ceylon, Bombay, Cochin (Malabar coast), and Madras, under the names of lemon-grass oil or citronnelle oil. It is yellow, and has a fragrant, citron-like odour. It is much used in perfumery under the name of oil of verbena. It is frequently adulterated with a fixed oil, and when thus sophisticated it forms a milky liquid when dropped into rectified spirit; whereas, the pure oil dissolves and yields a transparent solution.
The lemon-grass is employed in the form of infusion, in both the East and West Indies, as a mild diaphoretic in slight colds. The fresh leaves are sometimes used as a substitute for tea, and the white succulent centre of the leaf-bearing stems serves to give an agreeable flavour to curries. In Martinique, it is reputed poisonous, or at least as capable of producing abortion both in animals and the human species. [Guibourt, Hist. Nat. des Drogues Simples, 4me édit. t. ii. p. 114, 1819.]