Lavender Flowers; F. Fleurs de Lavande; G. Lavendelblumen.
Botanical Origin—Lavandula vera DC., a shrubby plant growing in the wild state from 1 to 2 feet high, but attaining 3 feet or more under cultivation. It is indigenous to the mountainous regions of the countries bordering the western half of the Mediterranean basin. Thus it occurs in Eastern Spain, Southern France (extending northward to Lyons and Dauphiny), in Upper Italy, Corsica, Calabria and Northern Africa,—on the outside of the olive region.[1738] In cultivation it grows very well in the open air throughout the greater part of Germany and as far north as Norway and Livonia; the northern plant would even appear to be more fragrant, according to Schübeler.[1739]
History—There has been much learned investigation in order to identify lavender in the writings of the classical authors, but the result has not been satisfactory, and no allusion has been found which unquestionably refers either to L. vera or to L. Spica,[1740] whereas L. Stœchas was perfectly familiar to the ancients.
The earliest mention of lavender that we have observed, occurs in the writings of the abbess Hildegard,[1741] who lived near Bingen on the Rhine during the 12th century, and who in a chapter De Lavendula alludes to the strong odour and many virtues of the plant. In a poem of the school of Salerno entitled Flos Medicinæ[1742] occur the following lines:—
In 1387 cushions of satin were made for King Charles VI. of France, to be stuffed with “lavende.”[1743] Its use was also popular at an early period in the British isles, for we find “Llafant” or “Llafanllys” mentioned among the remedies of the “Physicians of Myddvai.”[1744] And in Walton’s “Description of an inn,” about the year 1680 to 1690, we find the walls stuck round with ballads, where the sheets smelt of lavender....[1745]
Lavender was well known to the botanist of the 16th century.
Description—The flowers of Common Lavender are produced in a lax terminal spike, supported on a long naked stalk. They are arranged in 6 to 10 whorls (verticillasters), the lowest being generally far remote from those above it. A whorl consists of two cymes, each having, when fully developed, about three flowers, below which is a rhomboidal acuminate bract, as well as several narrow smaller bracts belonging to the particular flowers. The calyx is tubular, contracted towards the mouth, marked with 13 nerves and 5-toothed, the posterior tooth much larger than the others. The corolla of a violet colour is tubular, two-lipped, the upper lip with two, the lower with three lobes. Both corolla and calyx, as well as the leaves and stalks, are clothed with a dense tomentum of stellate hairs, amongst which minute shining oil-glands can be seen by the aid of a lens.
The flowers emit when rubbed a delightful fragrance, and have a pleasant aromatic taste. The leaves of the plant are oblong linear, or lanceolate, revolute at the margin and very hoary when young.
For pharmaceutical use or as a perfume, lavender flowers are stripped from the stalks and dried by a gentle heat. They are but seldom kept in the shops, being grown almost entirely for the sake of their essential oil.
Production of Essential Oil—Lavender is cultivated in the parishes of Mitcham, Carshalton and Beddington and a few adjoining localities, all in Surrey, to the extent of about 300 acres. It is also grown at Market Deeping in Lincolnshire; also at Hitchin in Hertfordshire, where lavender was apparently cultivated as early as the year 1568.[1746]
At the latter place there were in 1871 about 50 acres so cropped.
The plants which are of a small size, and grown in rows in dry open fields, flower in July and August. The flowers are usually cut with the stalks of full length, tied up in mats, and carried to the distillery there to await distillation. This is performed in the same large stills that are used for peppermint. The flowers are commonly distilled with the stalks as gathered, and either fresh, or in a more or less dry state. A few cultivators distill only the flowering heads, thereby obtaining a superior product. Still more rarely, the flowers are stripped from the stalks, and the latter rejected in toto.[1747] According to the careful experiments of Bell,[1748] the oil made in this last method is of exceedingly fine quality. The produce he obtained in 1846 was 26½ ounces per 100 lb. of flowers, entirely freed from stalks; in 1847, 25½ ounces; and in 1848, 20 ounces: the quantities of flowers used in the respective years were 417, 633, and 923 lb. Oil distilled from the stalks alone was found to have a peculiar rank odour. In the distillation of lavender, it is said that the oil which comes over in the earlier part of the operation is of superior flavour.
We have no accurate data as to the produce of oil obtained in the ordinary way, but it is universally stated to vary extremely with the season. Warren[1749] gives it as 10 to 12 lb., and in an exceptional case as much as 24 lb. from the acre of ground under cultivation. At Hitchin,[1750] the yield would appear to approximate to the last named quantity. The experiments performed in Bell’s laboratory as detailed above, show that the flowers deprived of stalks afforded on an average exactly 1½ per cent. of essential oil.
Oil of Lavandula vera is distilled in Piedmont, and in the mountainous parts of the South of France, as in the villages about Mont Ventoux near Avignon, and in those some leagues west of Montpellier (St. Guilhen-le-désert, Montarnaud and St. Jean de Fos)—in all cases from the wild plant. This foreign oil is offered in commerce of several qualities, the highest of which commands scarcely one-sixth the price of the oil produced at Mitcham.[1751] The cheaper sorts at least are obtained by distilling the entire plant.
Chemical Composition—The only constituent of lavender flowers that has attracted the attention of chemists is the essential oil (Oleum Lavandulæ). It is a pale yellow, mobile liquid, varying in sp. gr. from 0·87 to 0·94 (Zeller), having a very agreeable odour of the flowers and a strong aromatic taste. The oil distilled at Mitcham (1871) we find to rotate the plane of polarization 4·2° to the left, in a column of 50 mm.
Oil of lavender seems to be a mixture in variable proportions of oxygenated oils and stearoptene, the latter being identical, according to Dumas, with common camphor. In some samples it is said to exist to the extent of one-half, and to be sometimes deposited from the oil in cold weather; we have not however been able to ascertain this fact. The oil according to Lallemand (1859) appears also to contain compound ethers.
Commerce—Dried lavender flowers are the object of some trade in the south of Europe. According to the official Tableau général du Commerce de la France, Lavender and Orange Flowers (which are not separated) were exported in 1870 to the extent of 110,958 kilo. (244,741 lb.),—chiefly to the Barbary States, Turkey and America. There are no data to show the amount of oil of lavender imported into England.
Uses—Lavender flowers are not prescribed in modern English medicine. The volatile oil has the stimulant properties common to bodies of the same class and is much used as a perfume.
Other Species of Lavender.
1. Lavandula Spica DC. is a plant having a very close resemblance to L. vera, of which Linnæus considered it a variety, though its distinctness is now admitted. It occurs over much of the area of L. vera, but does not extend so far north, nor is it found in such elevated situations, or beyond the limit of the olive. It is in fact a more southern plant and more susceptible to cold, so that it cannot be cultivated in the open soil in Britain except in sheltered positions. In Languedoc and Provence, it is the common species from the sea-level up to about 2000 feet, where it is met by the more hardy L. vera.[1752]
Lavandula Spica is distilled in the south of France, the flowering wild plant in its entire state being used. The essential oil, which is termed in French Essence d’Aspic, is known to English druggists as Oleum Lavandulæ spicæ, Oleum Spicæ, or Oil of Spike. It resembles true oil of lavender, but compared with that distilled in England it has a much less delicate fragrance. This however may depend upon the frequent adulteration, for we find that flowers of the two plants (L. vera and L. Spica) grown side by side in an English garden, are hardly distinguishable in fragrance. Porta already even, in speaking of the oil of lavender flowers, stated:[1753] “e spica fragrantior excipitur, ut illud quod ex Gallia provenit....”—Lallemand (1859) isolated from oil of spike a camphor which he believes to be identical with common camphor.
Oil of Spike is used in porcelain painting and in veterinary medicine.
2. Lavandula Stœchas L.—This plant was well known to the ancients; Dioscorides remarks that it gives a name to the Stœchades, the modern isles of Hières near Toulon, where the plant still abounds. It has a wider range than the two species of Lavandula already described, for it is found in the Canaries and in Portugal, and eastward throughout the Mediterranean region to Constantinople and Asia Minor. It may at once be known from the other lavenders by its flower-spike being on a short stalk, and terminating in 2 or 3 conspicuous purple bracts.
The flowers, called Flores Stœchados or Stœchas arabica,[1754] were formerly kept in the shops, and had a place in the London Pharmacopœia down to 1746. We are not aware that they are, or ever were distilled for essential oil, though they are stated to be the source of True Oil of Spike.[1755]
Spearmint.
Botanical Origin—Mentha viridis L. is a fragrant perennial plant, chiefly known in Europe, Asia and North America, as the Common Mint of gardens, and only found apparently wild in countries where it has long been cultivated. It occurs occasionally in Britain under such circumstances.[1756]
Mentha viridis is regarded by Bentham as not improbably a variety of M. silvestris L., perpetuated through its ready propagation by suckers. J. G. Baker remarks, that while these two plants are sufficiently distinct as found in England, yet continental forms occur which bridge over their differences.[1757]
History—Mint is mentioned in all early mediæval lists of plants, and was certainly cultivated in the convent gardens of the 9th century. Turner, who has been called “the father of English botany,” states in his Herball[1758] that the garden mint of his time was also called “Spere Mynte.” We find spearmint also described by Gerarde who terms it Mentha Romana vel Sarracenica, or Common Garden Mint, but his statement that the leaves are white, soft, and hairy does not well apply to the plant as now found in cultivation.
Description—Spearmint has a perennial rootstock which throws out long runners. Its stem 2 to 3 feet high is erect, when luxuriant branched below with short erecto-patent branches, firm, quadrangular, naked or slightly hairy beneath the nodes, often brightly tinged with purple. Leaves sessile or the lower slightly stalked, lanceolate or ovate-lanceolate, rounded or even cordate at the base, dark green and glabrous above, paler and prominently veined with green or purple beneath, rather thickly glandular, but either quite naked or hairy only on the midrib and principal veins, the point narrowed out and acute, the teeth sharp but neither very close nor deep, the lowest leaves measuring about 1 inch across by 3 or 4 inches long. Inflorescence a panicled arrangement of spikes, of which the main one is 3 or 4 inches long by ⅜ inch wide, the lowest whorls sometimes ½ an inch from each other and the lowest bracts leafy. Bracteoles linear-subulate, equalling or exceeding the expanded flowers, smooth or slightly ciliated. Pedicels about ¾ line long, purplish glandular, but never hairy. Calyx also often purplish, the tube campanulato-cylindrical, ⅜ line long, the teeth lanceolate-subulate, equalling the tube, the flower part of which is naked, but the teeth and often the upper part clothed more or less densely with erecto-patent hairs. Corolla reddish-purple, about twice as long as the calyx, naked both within and without. Not smooth.
The plant varies slightly in the shape of its leaves, elongation of spike and hairiness of calyx. The entire plant emits a most fragrant odour when rubbed, and has a pungent aromatic taste.
Production—Spearmint is grown in kitchen gardens, and more largely in market gardens. A few acres are under cultivation with it at Mitcham, chiefly for the sake of the herb, which is sold mostly in a dried state.
The cultivation of spearmint is carried on in the United States in precisely the same manner as that of peppermint, but on a much smaller scale. Mr. H. G. Hotchkiss of Lyons, Wayne County, State of New York, has informed us that his manufacture of the essential oil amounted in 1870 to 1162 lb. The plant he employs appears from the specimen with which he has favoured us, to be identical with the spearmint of English gardens, and is not the Curled Mint (Mentha crispa) of Germany.
Chemical Composition—Spearmint yields an essential oil (Oleum Menthæ viridis) in which reside the medicinal virtues of the plant. Kane,[1759] who examined it, gives its sp. gr. as 0·914, and its boiling point as 160° C. The oil yielded him a considerable amount of stearoptene. Gladstone[1760] found spearmint oil to contain a hydrocarbon almost identical with oil of turpentine in odour and other physical properties, mixed with an oxidized oil to which is due the peculiar smell of the plant. The latter oil boils at 225° C.; its sp. gr. is 0·951, and it was found to be isomeric with carvol, C₁₀H₁₄O. According to our experiments the oil, distilled from Curled Mint grown in Germany, deviates the plane of polarization 37°·4 to the left when examined in a column of 100 millimetres. We prepared from it the crystallized compound (C₁₀H₁₄0)₂SH₂, and isolated from it the liquid C₁₀H₁₄O, which differs from carvol (see Fructus Carui, page 306) by its levogyrate power.[1761]
Uses—Spearmint is used in the form of essential oil and distilled water, precisely in the same manner as peppermint In the United States the oil is also employed by confectioners and the manufacturers of perfumed soap.
Substitutes—Oil of spearmint is now rarely distilled in England, its high cost[1762] causing it to be nearly unsaleable. The cheaper foreign oil is offered in price-currents as of two kinds, namely American and German. Of the first we have already spoken: the second, termed in German Krauseminzöl, is the produce of Mentha aquatica L. var. γ crispa Bentham, a plant cultivated in Northern Germany. Its oil seems to agree with the oil of spearmint.
Peppermint; F. Menthe poivrée; G. Pfefferminze.
Botanical Origin—Mentha piperita Hudson (non Linn.), an erect usually glabrous perennial, much resembling the Common Spearmint of the gardens, but differing from it in having the leaves all stalked, the flowers larger, the upper whorls of flowers somewhat crowded together, and the lower separate. In the opinion of Bentham it is possibly a mere variety of M. hirsuta L., with which it can be connected by numerous intermediate forms.
Peppermint rapidly propagates itself by runners, and is now found in wet places in several parts of England, as well as on the Continent. It is cultivated on the large scale in England, France, Germany, and North America.
History—Mentha piperita was first observed in Hertfordshire by Dr. Eales, and communicated to Ray, who in the second edition of his Synopsis Stirpium Britannicarum, 1696, noticed it under the name of Mentha spicis brevioribus et habitioribus, foliis Menthæ fuscæ, sapore fervido piperis; and in his Historia Plantarum[1763] as “Mentha palustris ... Peper-Mint.”[1764] Dale, who found the plant in the adjoining county of Essex, states[1765] that it is esteemed a specific in renal and vesical calculus; and Ray, in the third edition of his Synopsis, declares it superior to all other mints as a remedy for weakness of the stomach and for diarrhœa. Peppermint was admitted to the London Pharmacopœia in 1721, under the designation of Mentha piperitis sapore.
The cultivation of peppermint at Mitcham in Surrey dates from about 1750,[1766] at which period only a few acres of ground were there devoted to medicinal plants. At the end of the last century, above 100 acres were cropped with peppermint. But so late as 1805 there were no stills at Mitcham, and the herb had to be carried to London for the extraction of the oil. Of late years the cultivation has diminished in extent, by reason of the increased value of land and the competition of foreign oil of peppermint.
On the Continent Mentha Piperitis was grown as early as 1771 at Utrecht; Gaubius[1767] appears to have been the first to notice “Camphora Europæa Menthæ Piperitidis,” i.e. Menthol (see page 483).
In Germany peppermint became practically known in the latter half of the last century, especially through the recommendation of Knigge.[1768]
Description—The rootstock of peppermint is perennial, throwing out runners. The stem is erect, 3 to 4 feet high, when luxuriant somewhat branched below with erecto-patent branches, firm, quadrangular, slightly hairy, often tinged with purple. Leaves all stalked, the stalks of the lower ½ to ¾ of an inch long, naked or nearly so, the leaf lanceolate, narrowed or rather rounded towards the base, the point narrowed out and acute, the lowest 2 to 3 inches long by about ¾ of an inch broad, naked and dull green above, paler and glandular all over, but only slightly hairy upon the veins beneath; the teeth sharp, fine, and erecto-patent. Inflorescence in a loose lanceolate or acutely conical spike, 2 to 3 inches long by about ¾ of an inch broad at the base, the lowest whorls separate, and usually the lowest bracts leaf-like. Bracteoles lanceolate-acuminate, about equalling the expanded flowers, slightly ciliated. Pedicels 1 to 1½ lines long, purplish, glandular but not hairy. Calyx often purplish, the tube about 1 line long and the teeth ½ a line, the tube campanulate-cylindrical, purplish, not hairy, but dotted over with prominent glands; the teeth lanceolate subulate, furnished with short erecto-patent hairs. Corolla reddish-purple about twice as long as the calyx, naked both within and without. Nut smooth[1769] (rugose, according to our observation). The odour and taste are strongly aromatic.
In var. 2. vulgaris of Sole, M. piperita β. Smith, the plant is more hairy, with the spikes broader and shorter, or even bluntly capitate. colourless, pale yellow, or greenish liquid, of sp. gr. varying from 0·84 to 0·92. We learn from information kindly supplied by Messrs. Schimmel and Co., Leipzig, that the best peppermint grown in Germany, carefully dried, affords from 1 to 1·25 per cent. of oil. It has a strong and agreeable odour, with a powerful aromatic taste, followed by a sensation of cold when air is drawn into the mouth. We find that the Mitcham oil examined by polarized light in a column 50 mm. long, deviates from 14°·2 to 10°·7 to the left, American oil 4°·3.
Chemical Composition—The constituent for the sake of which peppermint is cultivated is the essential oil, Oleum Menthæ piperitæ, a coloureless, pale yellow or greenish liquid, of sp. gr. varying from 0·84 to 0·92. We learn from information kindly supplied by Messrs. Schimmel and Co., Leipzig, that the best peppermint grown in Germany, carefully dried from 1 to 1·25 per cent of oil. It has a strong and agreeable odour, with a powerful aromatic taste, followed by a sensation of cold when air is drawn into the mouth. We find that the Mitcham oil examined by polarized light in a column 50 mm. long, deviates from 14·2° to 10·7° to the left, American oil 4·2°.
When oil of peppermint is cooled to -4° C., it sometimes deposits colourless hexagonal crystals of Peppermint Camphor, C₁₀H₁₉OH, called also Menthol. We have never observed it, nor are we aware that menthol has been noticed in America, but it is largely afforded by eastern mints, and found in commerce under the name of Chinese or Japanese Oil of Peppermint,[1770] either liquid, and easily depositing the camphor, or also forming a crystalline mass impregnated with the liquid oil.
Pure menthol has the exquisite odour and taste of peppermint; it forms hexagonal crystals, melting at 42° C., and boiling at 212° C. By distilling menthol with P₂O₅ it yields menthene, C₁₀H₁₈, a levogyrate liquid, boiling at 163°, the peculiar odour of which reminds of peppermint.[1771] The Chinese crystallized oil of peppermint has sometimes a bitterish after-taste and an odour similar to that of spearmint, but by recrystallization it assumes the pure flavour.
The liquid part of the oil of peppermint has not yet been thoroughly investigated; it appears to consist chiefly of the compound C₁₀H₁₈O. Upon the liquid portions depend the remarkable colorations which the oil of peppermint is capable of assuming. If 50 to 70 drops of the crude oil are shaken with one drop of nitric acid, sp. gr. about 1·2, the mixture changes from faintly yellowish to brownish, and, after an hour or two, exhibits a bluish, violet or greenish colour; in reflected light, it appears reddish and not transparent. The colour thus produced lasts a fortnight. We have thus examined the various samples of peppermint oil at our command, and may state that the finest among them assume the most beautiful coloration and fluorescence, which, however, shows very appreciable differences. An inferior oil of American origin was not coloured; and a very old sample of an originally excellent English oil was likewise not coloured by the test. Menthol is not altered when similarly treated.[1772] The nitric acid test is not capable of revealing adulterations of peppermint oil, for the coloration takes place with an oil to which a considerable quantity of oil of turpentine has been added.
Remarkable colorations of a different hue are also displayed by the various kinds of oil of peppermint if other chemical agents are mixed with it. Thus green or brownish tints are produced by means of anhydrous chloral; the oil becomes bluish or greenish or rose-coloured if shaken with a concentrated solution of bisulphite of sodium. It is worthy of note that oils of different origin, which cannot be distinguished by means of nitric acid, exhibit totally different colorations if mixed with either of the liquids just named, or with vapour of bromine. This behaviour may be of some use in the examination of commercial sorts of peppermint oil.
As to bisulphite of sodium, it yields a solid compound with certain kinds of peppermint oil, which we have not yet examined.
Production and Commerce—In several parts of Europe, as well as in the United States, peppermint is cultivated on the large scale as a medicinal plant.
In England the culture is carried on in the neighbourhood of Mitcham in Surrey, near Wisebeach in Cambridgeshire, Market Deeping in Lincolnshire, and Hitchin in Hertfordshire.
At Mitcham in 1850 there were about 500 acres under cultivation; in 1864 only about 219 acres.[1773] At Market Deeping there were in 1871 about 150 acres cropped with peppermint. The usual produce in oil may be reckoned at 8 to 12 lb. per acre. The fields of peppermint at Mitcham are level, with a rich, friable soil, well manured and naturally retentive of moisture. The ground is kept free from weeds, and in other respects is carefully tilled. The crop is cut in August, and the herb is usually allowed to dry on the ground before it is consigned to the stills. These are of large size, holding 1000 to 2000 gallons, and heated by coal; each still is furnished with a condensing worm of the usual character, which passes out into a small iron cage secured by a padlock, in which stands the oil separator. The distillation is conducted at the lowest possible temperature. The water that comes over with the oil is not distilled with another lot of herb, but is for the most part allowed to run away, a very little only being reserved as a perquisite of the workmen. The produce is very variable, and no facilities exist for estimating it with accuracy.[1774] It is however stated that a ton of dried peppermint yields from 2½ to 3½ pounds of oil, which equals 0·11 to 0·15 per cent. But we have been assured by a grower at Mitcham that the yield is as much as 6 pounds from a ton, or 0·26 per cent.
At Mitcham and its neighbourhood two varieties of peppermint are at present recognized, the one being known as White Mint, the other as Black Mint, but the differences between the two are very slight. The Black Mint has purple stems; the White Mint, green stems, and as we have observed, leaves rather more coarsely serrated than those of the Black. The Black Mint is more prolific in essential oil than the White, and hence more generally cultivated; but the oil of the latter is superior in delicacy of odour and commands a higher price. White Mint is said to be principally grown for drying in bundles, or as it is termed “bunching.”
Peppermint is grown on a vastly larger scale in America, the localities where the cultivation is carried on being Southern Michigan, Western New York, and Ohio. In Michigan where the plant was introduced in 1855, there were in 1858 about 2100 acres devoted to its growth, all with the exception of about 100 acres being in the county of St. Joseph, where there are about 100 distilleries. The average produce of this district was estimated in 1858 at 15,000 lb.; but the yield fluctuates enormously, and in the exceptionally fine season of 1855 it was reckoned at 30,000 lb. We must suppose that it is sometimes much larger, for we have been informed by Mr. H. G. Hotchkiss, of Lyons, Wayne County, State of New York, one of the most well-known dealers, in a letter under date Oct. 10, 1871, that the quantity sent out by him in the previous year reached the enormous amount of 57,365 lb. It is further stated by the official statistics of Hamburg for the year 1876 that this port received 25,840 lb. of peppermint oil from the United States and 14,890 lb. from Great Britain.
From the statistics quoted by Stearns[1775] it would appear that the produce of oil per acre is somewhat higher in America than in England, but from various causes information on this head cannot be very reliable.
Peppermint is cultivated at Sens in the department of the Yonne in France[1776] and in Germany in the environs of Leipzig, where the little town of Cölleda produces annually as much as 40,000 cwts. of the herb.
The annual crop of the world is supposed to yield 90,000 lb. of peppermint oil.[1777]
Peppermint oil varies greatly in commercial value, that of Mitcham commanding twice or three times as high a price as the finest American. Even the oil of Mitcham is by no means uniform in quality, certain plots of ground affording a product of superior fragrance. A damp situation or badly drained ground is well known to be unfavourable to the quantity and quality of oil.
The presence of weeds among the peppermint is an important cause of deterioration to the oil, and at Mitcham some growers give a gratuity to their labourers to induce them to be careful in throwing out other plants when cutting the herb for distillation. One grower of peppermint known to us was compelled to abandon the cultivation, owing to the enormous increase of Mentha arvensis L. which could not be separated, and which when distilled with the peppermint ruined the flavour of the latter. In America great detriment is occasioned by the growth of Erigeron canadensis L. Newly cleared ground planted with peppermint is liable to the intrusion of another plant of the order Compositæ, Erechtites hieracifolia Raf., which is also highly injurious to the quality of the oil.[1778]
Uses—A watery or spirituous solution of oil of peppermint is a grateful stimulant, and is a frequent adjunct to other medicines. Oil of peppermint is extensively consumed for flavouring and cordials.
Pennyroyal[1779]; F. Menthe pouliot, Pouliot vulgaire; G. Polei.
Botanical Origin—Mentha Pulegium L., a small perennial aromatic plant, common throughout the south of Europe and extending northward to Sweden, Denmark, England and Ireland, eastward to Asia Minor and Persia, and southward to Abyssinia, Algeria, Madeira and Teneriffe. It has been introduced into North[1780] and South America. For medicinal use it is cultivated on a small scale.
History—Pennyroyal was in high repute among the ancients. Both Dioscorides and Pliny describe its numerous virtues. In Northern Europe it was also much esteemed, as may be inferred from the frequent reference to it in the Anglo-Saxon and Welsh works on medicine.
Gerarde considered the plant to be “so exceedingly well known to all our English nation” that it needed no description. In his time (circa 1590), it used to be collected on the commons round London, whence it was brought in plenty to the London markets. At the present day pennyroyal has fallen into neglect, and is not named in the British Pharmacopœia of 1867.
Description—The plant has a low, decumbent, branching stem, which in flowering rises to a height of about 6 inches. Its leaves, scarcely an inch in length and often much less, are petiolate, ovate, blunt, crenate at the margin, dotted with oil-glands above and below. The flowers are arranged in a series of dense, globose whorls, extending for a considerable distance up the stem. The whole plant is more or less hairy. It has a strong fragrant odour, less agreeable to most persons than that of peppermint or spearmint. Its taste, well perceived in the distilled water, is highly aromatic.
Chemical Composition—The most important constituent of pennyroyal is the essential oil, known in pharmacy as Oleum Pulegii, to which is due the odour of the plant. It has been examined by Kane,[1781] according to whom it has a sp. gr. of 0·927. Its boiling was found to fluctuate between 183° and 188° C. The formula assigned to it by this chemist is C₁₀H₁₆O. We ascertained that it contains no carvol (see page 481.)
Production—Pennyroyal is cultivated at Mitcham and is mostly sold dried; occasionally the herb is distilled for essential oil. The oil found in commerce is however chiefly French or German, and far less costly than that produced in England.
Uses—The distilled water of pennyroyal is carminative and antispasmodic, and is used in the same manner as peppermint water.
Garden Thyme; F. Thym vulgaire; G. Thymiankraut.
Botanical Origin—Thymus vulgaris L., a small, erect, woody shrub reaching 8 to 10 inches in height, gregarious on sterile uncultivated ground in Portugal, Spain, Southern France and Italy, and in the mountainous parts of Greece. On Mont Ventoux near Avignon, it reaches an elevation above the sea of 3700 ft. (Martins). It is commonly cultivated in English kitchens as a sweet herb,[1782] and succeeds as an annual even in Iceland.
History—We are not aware that thyme had any reputation in the antiquity, nor do we know at what period it was first introduced in northern countries. Garden thyme was commonly cultivated in England in the 16th century, and was well figured and described by Gerarde. It is even said to have been formerly grown on a large scale for medicinal use in the neighbourhood of Deal and Sandwich in Kent.[1783] Camphor of Thyme was noticed by Neumann, apothecary to the Court at Berlin in 1725;[1784] it was called Thymol, and carefully examined in 1853 by Lallemand, and recommended instead of phenol (carbolic acid) in 1868 by Bouilhon, apothecary, and Paquet, M. D. of Lille.
Description—The plant produces thin, woody, branching stems, bearing sessile, linear-lanceolate, or ovate-lanceolate leaves. These are about ¼ of an inch long, revolute at the margin, more or less hoary, especially on the under side, and dotted with shining oil-glands. The small purple flowers are borne on round terminal heads, with sometimes a few lower whorls. The entire wild plant has a greyish tint by reason of a short white pubescence, yet as seen in gardens the plant is more luxuriant, greener and far less tomentose. It is extremely fragrant when rubbed, and has a pungent aromatic taste.
Production of Essential Oil—Though cultivated in gardens for culinary use, common thyme is not grown in England on a large scale. Its essential oil (Oleum Thymi), for which alone it is of interest to the druggist, is distilled in the south of France. In the neighbourhood of Nîmes, where we have observed the process, the entire plant is used, and the distillation is carried on at two periods of the year, namely in May and June when the plant is in flower, and again late in the autumn. The oil has a deep, reddish-brown colour, but becomes colourless though rather less fragrant by re-distillation. The two sorts of oil, termed respectively Huile rouge de Thym and Huile blanche de Thym, are found in commerce. The yield is about 1 per cent.
Oil of thyme is frequently termed in English shops Oil of Origanum, which it in no respect resembles, and which was never, so far as we know, found in commerce.[1785]
Chemical Composition—The only constituent of the herb that has attracted any attention is the above-named essential oil. This liquid by fractional distillation is resolved into two portions: the first, more volatile and boiling below 180° C., is a mixture of two hydrocarbons, Cymene, C₁₀H₁₄ (see page 333), and Thymene, C₁₀H₁₆, the latter boiling at 165° C.
The second, named Thymol, C₁₀H₁₄O, which may also be extracted from the crude oil by means of caustic lye, has been described in our article Fructus Ajowan, at page 303. Commercial oil of thyme is said to be sometimes fraudulently deprived of thymol by that treatment.
Uses—Oil of thyme is an efficient external stimulant, and is sometimes employed as a liniment. Its chief consumption is in veterinary medicine. Thymol has been proposed as a disinfectant in the place of carbolic acid, in cases in which the odour of the latter is objectionable. The herb is not used in modern English medicine, but is often employed on the Continent.
Herba Anthos; Rosemary; F. Romarin; G. Rosmarin.
Botanical Origin—Rosmarinus officinalis L., an evergreen shrub, attaining a height of 4 feet or more, abundant on dry rocky hills of the Mediterranean region, from the Spanish peninsula[1786] to Greece and Asia Minor. It generally prefers the neighbourhood of the sea, but occurs even in the Sahara, where it is collected and conveyed by caravans to Central Africa.[1787] It does not succeed well in Germany.
History—Rosemary[1788] is mentioned by Pliny, who ascribes to it numerous virtues. It was also familiar to the Arab physicians of Spain, one of whom, Ibn Baytar (13th cent.), states it to be an object of trade among the vendors of aromatics.[1789] In the middle ages rosemary was doubtless much esteemed, as may be inferred from the fact that it was one of the plants which Charlemagne ordered to be grown on the imperial farms.
It was probably in cultivation in Britain prior to the Norman Conquest, as it is recommended for use in an Anglo-Saxon herbal of the 11th century.[1790] In the “Physicians of Myddvai” a curious chapter[1791] is devoted to the virtues of Rosemary, called “Ysbwynwydd, and Rosa Marina in Latin.” The essential oil was distilled by Raymundus Lullus[1792] about a.d. 1330. John Philip de Lignamine,[1793] a writer of the 15th century, describes Rosemary as the usual condiment of salted meats.
Description—Rosemary has sessile, linear, entire, opposite leaves about an inch in length, revolute at the margin; they are of coriaceous texture, green and glabrous above, densely tomentose and white beneath. Examined under a lens, the tomentum both of the leaves and young shoots is seen to consist of white stellate hairs; in that of the shoots which is less dense, minute oil-glands are discernible. These glands are of two kinds, large and small, and probably do not yield one and the same oil. The flowers have a campanulate 2-lipped calyx, and a pale blue and white corolla, the upper lip of which is emarginate and erect, the lower 3-lobed with the central lobe concave and pendulous. The whole plant has a very agreeable smell and a strong aromatic taste. It flowers in the early spring.
Production of Essential Oil—Rosemary is cultivated on a very small scale in English herb-gardens, and though a little oil has been occasionally distilled from it, English oil of rosemary is an article practically unknown in commerce. That with which the market is supplied is produced in the south of France and on the contiguous coasts of Italy. The plant, which is plentifully found wild, is gathered in summer (not while in flower) and distilled, the operator being sometimes an itinerant herbalist who carries his copper alembic from place to place, erecting it where herbs are plentiful, and where a stream of water enables him to cool a condenser of primitive construction.
Oil of rosemary is also produced on a somewhat large scale in the island of Lesina, south of Spalato in Dalmatia, whence it is exported by way of Trieste, even to France and Italy, to the extent of 300 to 350 quintals annually.[1794]
Some of the French manufacturers of essences offer oil of rosemary at a superior price as drawn from the flowers, by which we presume is meant the flowering tops, for the separation of the actual flowers would be impracticable on a large scale. The great bulk of the oil found in commerce is however that distilled from the entire plant.
Chemical Composition—The peculiar odour of rosemary depends on the essential oil, which is the only constituent of the plant that has afforded matter for chemical research.
Lallemand (1859) by fractional distillation, resolved oil of rosemary into two liquids,—the one a mobile hydrocarbon boiling at 165° C. and turning the plane of polarization to the left; the other, boiling between 200° and 210° C., deposits when exposed to a low temperature a large quantity of camphor. Gladstone (1864) found the oil to consist almost wholly of a hydrocarbon, C₁₀H₁₆. This, according to our experiments, constitutes about ⁴/₅ of the oil; it deviates the plane of polarization to the left, whereas a fraction boiling at 200° to 210° C. deviates to the right. By warming the latter with nitric acid, we observed the odour of common camphor, and may therefore infer that a compound, C₁₀H₁₈O, is present in the oil under examination.
From Montgolfier’s investigations (1876) it would appear that the stearoptene or camphor above alluded to is a mixture of a dextrogyrate and a lævogyrate substance.
Uses—The flowering tops and dried leaves are kept by the herbalists, but are not used in regular medicine. The volatile oil is employed as an external stimulant in liniments, and also as a perfume. Rosemary is popularly supposed to promote the growth of the hair.