Herb: Giant Ragweed

Latin name: Ambrosia trifida

Family: Compositae

Medicinal use of Giant Ragweed:

The leaves are very astringent, emetic and febrifuge. They are applied externally to insect bites and various skin complaints, internally they are used as a tea in the treatment of pneumonia, fevers, nausea, intestinal cramps, diarrhoea and mucous discharges. The juice of wilted leaves is disinfectant and is applied to infected toes. A tea made from the roots is used in the treatment of menstrual disorders and stroke. The pollen is harvested commercially and manufactured into pharmaceutical preparations for the treatment of allergies to the plant.

Description of the plant:


2 m
(6 1/2 foot)

August to

Habitat of the herb:

Alluvial waste places, sometimes forming vast pure stands.

Edible parts of Giant Ragweed:

This plant was cultivated by the pre-Columbian N. American Indians, seeds found in pre-historic sites are 4 - 5 times larger than those of the present-day wild plant, which seems to indicate selective breeding by the Indians. The following report is for A. artemesifolia, it quite possibly also applies to this species. An oil is obtained from the seed. It has been suggested for edible purposes because it contains little linolenic acid. The seed contains up to 19% oil, it has slightly better drying properties than soya bean oil.

Other uses of the herb:

A red colour is obtained from the crushed heads. (This probably refers to the seed heads.) The sap of the plant can stain the skin red.

Propagation of Giant Ragweed:

Seed - we have no details for this species but suggest sowing the seed in situ in April.

Cultivation of the herb:

Alluvial waste places, sometimes forming vast pure stands.

Known hazards of Ambrosia trifida:

The pollen of this plant is a major cause of hayfever in N. America. Ingesting or touching the plant can cause allergic reactions in some people.

Plant information taken from the Plants For A Future.