Common Name: Pigweed

General Information

Amaranthus retroflexus is an erect, annual plant with a stem that can be unbranched or branched only near the top; it can grow 20 - 150cm tall, occasionally to 200cm[, ].
The plant was at one time cultivated by the native north Americans for its edible leaves and seeds. It is still sometimes gathered from the wild and used locally.
The plant has spread as a weed from its original range in the American tropics and can now be found as a weed of cultivated and disturbed ground in many parts of the world[].

Known Hazards

No members of this genus are known to be poisonous, but when grown on nitrogen-rich soils they are known to concentrate nitrates in the leaves. This is especially noticeable on land where chemical fertilizers are used. Nitrates are implicated in stomach cancers, blue babies and some other health problems. It is inadvisable, therefore, to eat this plant if it is grown inorganically.

Botanical References

,

Range

Tropical America.

Habitat

A casual of cultivated land and waste places in Britain[]. Thrives in cultivated fields, home gardens, waste places and on ditch banks. It prefers open, sunny areas and appears quickly when soil is disturbed[].

Properties

Weed Potential	Yes
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Annual
Height	0.90 m
Pollinators	Wind, Self
Self-fertile	Yes
Cultivation Status	Cultivated, Wild

Cultivation Details

Originally a tropical plant, it can be found as a weed from the temperate zone through to the tropics.
Prefers a well-drained fertile soil in a sunny position[]. Requires a hot sheltered position if it is to do well[].
Plants are particularly susceptible to attacks by leaf-chewing insects[].
Plants should not be given inorganic fertilizers, see notes above on toxicity.
A good companion for potatoes, onions, corn, tomatoes, peppers and aubergines[, ].
A deep rooted plant, bringing up minerals from lower levels of the soil[].
Formerly cultivated as a food crop by the native N. Americans[].
Most if not all members of this genus photosynthesize by a more efficient method than most plants. Called the 'C4 carbon-fixation pathway', this process is particularly efficient at high temperatures, in bright sunlight and under dry conditions[].

Edible Uses

Young leaves - raw or cooked as a spinach[, , , , ]. A mild flavour, it is often mixed with stronger flavoured leaves[]. Very rich in iron, it is also a good source of vitamins A and C[].

Seed - raw or cooked[, , , ]. Ground into a powder and used as a cereal substitute[], it can also be sprouted and added to salads. The seed is very small, about 1mm in diameter[], but easy to harvest and very nutritious. The flavour is greatly improved by roasting the seed before grinding it[]. It is often added to maize meal[]. The seed can be cooked whole, and becomes very gelatinous like this, but it is rather difficult to crush all of the small seeds in the mouth and thus some of the seed will pass right through the digestive system without being assimilated[].

Medicinal

A tea made from the leaves is astringent[]. It is used in the treatment of profuse menstruation, intestinal bleeding, diarrhoea etc[, , ]. An infusion has been used to treat hoarseness[].

Other Uses

Yellow and green dyes can be obtained from the whole plant[].

Propagation

Seed - sow late spring in situ. An earlier sowing can be made in a greenhouse and the plants put out after the last expected frosts. Germination is usually rapid and good if the soil is warm[], but poor germination rates are experienced in cool or cold soils[]. A drop in temperature overnight aids germination[].
Cuttings of growing plants root easily[].