Bishop's weed is a small, erect, annual shrub, with soft fine' hairs. It has many' branched leafy stems; feather-like leaves 2.5 cm long; and 4 to 12 ray flower heads, each bearing 6 to 16 flowers. The fruits are minute, egg-shaped and greyish.
The trade name ajwain is based on the Indian name which is derived from adarjawan. Ajwain or Bishop's weed has been used as a carminative medicine from the time of Charaka and Sushruta. Even Greek physicians like Dioscrides and Gelen used it in various carminative medicines. Some very valuable Unani medicines are prepared from ajwain seeds. Bishop's weed is cultivated in Iran, Egypt, Afghanistan and India.
An analysis of the ajwain seeds shows them to consist of moisture 7.4 per cent, protein 17.1 per cent, fat 21.8 per cent, minerals 7.9 per cent, fibre 21.2 per cent and carbohydrates 24.6 per cent per 100 grams. Calcium, phosphorus, iron, carotene, thiamine, riboflavin and niacin are amongst the vitamins and minerals in it. Its calorific value is 363. Steam distillation of crushed seeds yields an essential oil which is valued considerably in medicine on account of the presence of thymol. The oil was, for a long time, the chief source of thymol.
The seeds are stimulant and are useful in counteracting spasmodic disorders. The oil of ajwain is an almost colourless to brownish liquid with characteristic odour and a sharp hot taste. If the liquid is allowed to remain undisturbed, a part of the thymol may separate from the crystals, which is sold in Indian markets under the name of ajwain ka phul or sat ajwain. It is much valued in medicine as it has nearly all the properties ascribed to the ajwain seeds.
Bishop's weed has long been used in indigenous medicine for the treatment of diarrhoea, dysentery, atonic dyspepsia, cholera, colic, flatulence and indigestion. For relieving flatulence, dyspepsia and spasmodic disorders, the seeds may be eaten with betel leaves. A teaspoon of these seeds with a litte rock-salt is a household remedy for indigestion.
The volatile oil extracted from the seeds is also useful in cholera, flatulent colic, diarrhoea, atonic dyspepsia and indigestion. It is usually given in doses of I to 3 drops. Omum water, that is, the water distilled from the seeds, is an excellent carminative that relieves flatulence and is antispasmodic in colic and flatulent dyspepsia. It is also administered in the early stages of cholera in doses of 30 to 60 grams to check vomiting. In case of colic, ajwain, dry ginger and black salt in the proportion of I : 1/ 2 : l/4 should be ground together and taken in three gram doses with warm water. In case of flatulence. ajwain and dried ginger in equal weight may be soaked in two and-half times the quantity of lime juice. This is then dried and powdered with a little black Salt. About two grams of this powder is taken with warm water.
A mixture of the seeds and buttermilk is an effective remedy for relieving difficult expectoration caused by dried up phlegm. The seeds are also efficacious in bronchitis. A hot fomentation with the seeds is a popular household remedy for asthma. Chewing a pinch of ajwain seeds with a crystal of common salt and a clove is a very effective remedy for cough caused by acute pharyngitis in influenza.
Bishop's weed is an effective common cold remedy. It has a remarkable power to open up clogged and congested nasal passages. A tablespoon of seeds crushed and tied up in a cloth bundle can be used for inhalation. A similar bundle placed near the pillow, while sleeping, also relieves nasal congestion. For infants and small children, a small pouch can be pinned to their dress under the chin when they are sleeping. In case of adults, a teaspoon of the seeds can be put in boiling water and the vapours inhaled.
The seeds are useful in the treatment of migraine and deIerium. They should either be smoked or sniffed frequently to obtain relief.
The oil extracted from the seeds is beneficial in the treatment of rheumatic and neuralgic pains. It should be applied ' on the affected parts.
An infusion of the seeds mixed .with common salt is an effective gargle in acute pharyngitis. sore and congested throat and hoarseness of the voice due to colds or shouting.
The herb is beneficial in earache. About half a teaspoon of the seeds is heated in 30 ml of milk till the essence of the seeds permeate the milk. The milk is then filtered and used as ear drops. It decreases congestion and relieves pain. In case of pain caused by boils in the ear, 3 grams each of ajwain seeds and garlic are boiled together in 40 grams of sesame oil till they turn red. The oil is then strained and cooled to body temperature, and used as ear drops.
Aphrodisiac: Ajwain seeds, combined with the kernel of tamarind seeds are an effective aphrodisiac. These should be fried in equal quantity of pure ghee, powdered and preserved in airtight containers. A teaspoon of this powder, mixed with a tablespoon of honey, taken daily with milk before retiring, makes an excellent aphrodisiac. It increases virility and cures premature ejaculation.
The greyish brown fruits or seeds are used as a spice, in flavouring numerous foods, as anti-oxidants, preservatives and in medicine.