Fennel

FENNEL

Synonyms

Fructus foeniculli, Fennel fruit, Fenkel, Florence fennel, Sweet fennel, Wild fennel, Large fennel.

Biological Source

Fennel consists of the dried ripe fruits of Foeniculum vulgare Miller., belonging to family Umbelliferae.

Geographical Source

Fennel is indigenous to Mediterranean countries and Asia; it is largely cultivated in France, Saxony, Japan, Galicia, Russia, India, and Persia.

History

Fennel was well-known to the Ancients, and it was also cultivated by the ancient Romans for its aromatic fruits and edible shoots. It is reported that during third-century B.C. Hippocrates prescribed fennel for the treatment of infant colic, and later on after 400 years Dioscorides called fennel as an appetite suppressant and recommended the seeds for nursing mothers to increase milk secretion. Pliny suggested that fennel cured eye problems and jaundice. Fennel seeds are commonly taken after meals to prevent gas and stomach upset. The use of fennel shoots and seeds are mentioned in ancient record of Spanish agriculture dating A.D. 961.

Cultivation and Collection

Fennel, a hardy, beautiful plant, perennial, umbelliferous herb, with yellow flowers and feathery leaves, grows wild in many parts of the world. Fennel is propagated by seeds during April in ordinary soil. Fennel requires abundance sun light and is adapted to dry in sunny situations, it does not call for heavily manured ground but it will yield more on well-drained calcareous soil. About 4 1/2 to 5 lb of seed are sown per acre, either in drills or 15 inches apart, evenly covered with soil. The plants grow to a height of 2 m, erect and cylindrical and take enough space in branching. Most of the branches bearing leaves cut into the very finest of segments. The plant bears fruits in the second year and the bright golden flowers, flat terminal umbels bloom in July and August. The fruits are collected by cutting the stems in September, when the fruits are ripe. The stems are dried on sheaves under sun and later beaten to separate the fruits.

Characteristics

The fruit is an entire cremocarps with pedicels, oval-oblong and 5 to 10 mm long, 2 to 4 mm broad. It has greenish-brown to yellowish brown colour with five prominent primary ridges and a bifid stylopod at the apex.

                          Foeniculum vulgare

Microscopy

The transverse section of mericarp region of fennel shows two prominent surfaces, the dorsal and the commissural surface. The commisural surface has a carpophore and two vittae, and the dorsal surface has a total of five ridges. The mericarp is divided into pericarp, consisting of the epicarp and mesocarp; the testa and the endocarp. Epicarp consists of polygonal cells of epidermis which are tangentially elon-gated and covered by the cuticle. Mesocarp has parenchyma cells with five bicollateral vascular bundles; below each primary ridge a lignified reticulate parenchyma surrounds the vascular bundles. There are four vittae on dorsal surface and two vittae on commisural or the ventral surface. Inner Epidermis or Endocarp shows parquetry arrangement (a group of four to five cells arranged parallelly at acute angles with groups of similar cells in different direction). Testa is a single-layered tangentially elongated cell with yellowish colour. Endosperm consists of thick-walled, wide polyhedral, colourless cells. Cells contain fixed oil, aleurone grains, and rosette crystals of calcium oxalate.

         Transverse section of Fennel fruit (Mericarp)

                             T.S. (schematic) of Fennel fruit

Chemical Constituents

The best varieties of Fennel contain 4 to 5% of volatile oil. The primary constituents of volatile oil are 50 to 60% of anethole, a phenolic ester; and 18 to 22% of fenchone, a ketone. Fenchone is chemically a bicyclic monoterpene which is a colourless liquid and the odour and taste is pungent and camphoraceous. The oil of Fennel has β-pinene, anisic acid, phellandrine, and anisic aldehyde. Fennel also contains about 20% fixed oil and 20% proteins.

Uses

Fennel is used as stomachic, aromatic, diuretic, carminative, diaphoretic, as a digestive, pectoral, and flavouring agent. Anethole may have estrogen-like activity and inhibit spasms in smooth muscles. Fennel can increase production of bile, used in the treatment of infant colic, to promote menstrua-tion in women, can increase lactation, act as antipyretic, antimicrobial and antiinflammatory.

Adulterants

Fennel is generally adulterated with exhausted fennel and due to improper caring during harvesting they are also adulterated with sand, dirt, stem, weed seeds, etc in which part of volatile oil is removed either by extraction with alcohol or steam distillation. Fruits exhausted by water or steam are darker in colour, contain less essential oil and sink in water, but those exhausted by alcohol still hold 1 to 2% of oil in them.

Marketed Products

It is one of the ingredients of the preparations known as Abana, Shahicool, Anxocare (Himalaya Drug Company), Aptikid (Lubin Herbal Laboratory), Jalifaladi bati (Baidyanath), and Hajmola, Janum Gunti (Dabur).