Common Name: Black Nightshade

General Information

Solanum nigrum is an erect, much-branched annual plant growing around 60cm tall.
The plant is harvested from the wild for local use as a food and medicine. Some forms of this plant are occasionally cultivated, especially in western Africa and tropical Asia, for their edible fruits or leaves[, ]. The plant also has potential for use in soil remedial programmes for removing PCB's from the soil.
Black nightshade is a common weed of many areas of the world, being found in gardens, fields, waste areas and open forests. It is mainly a weed of moist environments, and thrives in areas of low rainfall only where the land is under irrigation[].

Known Hazards

There is a lot of disagreement over whether or not the leaves or fruit of this plant are poisonous. Views vary from relatively poisonous to perfectly safe to eat. The plant is cultivated as a food crop, both for its fruit and its leaves, in some parts of the world and it is probably true to say that toxicity can vary considerably according to where the plant is grown and the cultivar that is being grown[, , , , , ]. The unripe fruit contains the highest concentration of toxins[].

Botanical References

,

Range

Found throughout most of the world, including Britain

Habitat

Uncultivated and waste land[]. It is a common garden weed.

Properties

Weed Potential	Yes
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Annual
Height	0.60 m
Pollinators	Insects
Cultivation Status	Cultivated, Wild

Cultivation Details

Black nightshade is found through most of the world from the temperate zone to the tropics. It succeeds in the tropics at elevations from sea level to 3,000 metres[, ]. It grows best in areas where annual daytime temperatures are within the range 21 - 28°c, but can tolerate 8 - 40°c[]. It prefers a mean annual rainfall in the range 1,000 - 1,600mm, but tolerates 500 - 2,700mm[].
Grows best in full sun, but plants tolerate a reasonable level of shade[]. An easily grown plant, it succeeds in most soils[], growing best when there is a high content of organic matter in the soil[]. Intolerant of dry conditions according to one report[], whilst another says that they are very tolerant of dry soils[]. Prefers a pH in the range 6.5 - 7.5, tolerating 4.3 - 8.5[].
A first harvest of the leaves can take place about 2 - 3 months after sowing the seed[].
There are some named forms[].
Caterpillars and slugs are particularly fond of this plant and can totally destroy it[].
Grows well with clover[]. Does not grow well with wormwood or white mustard and, when these plants are growing close to S. Nigra, they increase its content of toxic alkaloids[].

Edible Uses

Fruit - cooked[, , , ]. Used in preserves, jams and pies[]. A pleasant musky taste[]. Somewhat like a tomato, but much less pleasant, it improves slightly after a frost[]. Only the fully ripe fruits should be used, the unripe fruits contain the toxin solanine[, , ]. The fruit contains about 2.5% protein, 0.6% fat, 5.6% carbohydrate, 1.2% ash[]. The fruit is about 9mm in diameter[].

Young leaves and new shoots - raw or cooked as a potherb or added to soups[, , , , , , ]. This plant is cultivated as a leaf crop in some areas, but see the notes at the top of the page regarding possible toxicity.

Medicinal

The whole plant is alterative, antiperiodic, antiphlogistic, aphrodisiac, diaphoretic, diuretic, emollient, febrifuge, laxative, narcotic, purgative, sedative, stimulant and tonic[, , , , , , ]. It is harvested in the autumn when both flowers and fruit are upon the plant, and is dried for later use[]. Use with caution[], see notes above on toxicity.
The leaves, stems and roots are used externally as a poultice, wash etc in the treatment of cancerous sores, boils, leucoderma and wounds[, , ].
Extracts of the plant are analgesic, antispasmodic, anti-inflammatory, sedative, vasodilator and vulnerary[, ]. The plant has been used in the manufacture of locally analgesic ointments and the juice of the fruit has been used as an analgesic for toothaches[].
A tincture of the leaves is said to alleviate neuralgic pains[].

The ripe fruit is alterative, aphrodisiac, diuretic and laxative[]. It is used in the treatment of fevers, diarrhoea, eye diseases and rabies[]. A paste of the unripe fruit is used as a poultice to treat headaches and ringworm[].

Other Uses

This species has been found to be effective in removing Polychlorinated biphenyls (PCB's) from the soil and detoxifying them[]. The plant is more effective in doing this if it is infected with the bacterial parasite Agrobacterium tumefaciens[].

An extract of the whole plant is used as an ingredient in commercial cosmetic preparations as a skin conditioner[].

Propagation

Seed - sow spring in situ.
The seed can also be sown in a greenhouse during the spring if required. Prick out the seedlings into individual pots when they are large enough to handle and plant out in late spring.