Source, Etc

Fennel, Foeniculum capillaceum, Gilibert (F. vulgare, Miller; N.O. Umbelliferoe), is apparently indigenous to the shores of the Mediterranean, extending eastwards, but is cultivated for medicinal use in the south of France, in Saxony and Wurtemberg, in Russia and Galicia, and also in India, Japan, etc. Like other aromatic Umbelliferous fruits, fennel was well known to the ancients, and was largely used in Europe during the Middle Ages. For medicinal use Saxon, Russian, Galician, or Roumanian fruits are to be preferred, as it has been shown that they yield most volatile oil, and that the latter contains fenchone (see below).

Description

Fennel fruits occur in several commercial varieties, varying considerably in size and appearance. Saxon fruits, which may be regarded as the best, are of a greenish or yellowish brown colour, and oblong in shape, varying from 8 to 10 mm. in length, and 3 to 4 mm. in width. The mericarps frequently remain united and attached to a pedicel. They are glabrous, and bear five paler, very prominent, primary ridges. In a transverse section four large vittae can be distinguished by the naked eye on the dorsal surface, and two on the commissural surface of each mericarp; the endosperm is dark in colour, oily, and not deeply grooved. They have an aromatic odour, recalling anise, and a sweet, camphoraceous taste.

The student should observe

(a) The very prominent ridges,

(6) The large vittoe,

(c) The characteristic odour and taste.

Constituents

The best varieties of fennel (Saxon, Galician, and Russian) yield from 4 to 5 per cent, of volatile oil (sp. gr. 0.960 to 0.980; O.R.+ 6° to + 12°; sohdifying-point 5° to 20°), the principal constituents of which are anethol (C10H12O, 50 to 60 per cent.) and fenchone (C10H16O, 18 to 20 per cent.).

Anethol is also the chief constituent of anise oil (compare p. 121).

Fenchone is a colourless liquid possessing a pungent, camphoraceous odour and taste; it probably contributes materially to the medicinal properties of the oil, hence only such varieties of fennel as contain a good proportion of fenchone are suitable for medicinal use.

Varieties

The following are the chief commercial varieties of fennel fruits:

1. Saxon: as above described; they yield 4.7 per cent, of volatile oil containing 22 per cent, of fenchone.

2. Russian, Galician, and Roumanian: these closely resemble one another; from 4 to 6 mm. in length and 1 to 2 mm. in width; yield of oil from 4 to 5 per cent, of which about 18 per cent, is fenchone; taste very camphoraceous.

Fig. 63.   Fennel fruit. A, entire fruit, side view, magnified 3 diam. B, half fruit, showing commissural surface, magnified 3 diam. C, transverse section; μ, vittae; k, ridges; 2, endosperm; 3, embryo; magnified 14 diam. D, portion of the same, further enlarged. (Berg.)

Fig. 63. - Fennel fruit. A, entire fruit, side view, magnified 3 diam. B, half-fruit, showing commissural surface, magnified 3 diam. C, transverse section; μ, vittae; k, ridges; 2, endosperm; 3, embryo; magnified 14 diam. D, portion of the same, further enlarged. (Berg).

3. French Sweet or Roman, 7 to 8 mm. long, 2 to 3 mm. wide, often arched; pale yellowish green with a sweet, anise taste. Yield of oil 21 per cent., free from fenchone.

4. Indian, 6 to 7 mm. long, brownish, stalky, with sweet anise taste. Yield of oil 0.72 per cent., containing 6.7 per cent, of fenchone.

5. Japanese, 3 to 4 mm. long, 2 to 3 mm. wide, ovoid, not curved, pale greenish brown in colour; taste camphoraceous and very sweet. Yield of oil 2.7 per cent., containing 102 per cent, of fenchone.

6. French Bitter, 4 to 5 mm. long, 2 mm. wide, scurfy in the furrows, ridges less prominent, and colour darker than the sweet.

Adulteration

Fennel is said to be specially subject to admixture with exhausted fruits. These include the fruits partially exhausted of their oil by distillation in a current of alcohol vapour in liqueurmaking, as well as the residues obtained after distillation with water or in a current of steam. Fruits exhausted by water or steam are darker, contain less oil, and sink at once in water, but those exhausted by alcohol vapour retain TO to 2.0 per cent, of oil, and are but little altered in appearance; they acquire, however, a peculiar fusel-oil odour. Recoloured fennel may be detected by rubbing the fruits between the hands.

Uses

Fennel is used as an agreeable aromatic and carminative.