Ambrosia trifida - Giant Ragweed

Family:	Compositae
Habit:	Annual
Height:	2
Synonyms:
Range:	Eastern N. America - Quebec to Florida, west to Manitoba, Colorado and Mexico.

Ambrosia trifida (Giant Ragweed) is a Annual which grows to a height of 2m . It has a hardness rating of 0.
Giant Ragweed will flower in February to April. The flowers from this plant are monoecious (both sexes are found on the plant but each flower is either male or female) and they are pollinated by Wind

Soil Information

Giant Ragweed will grow in light (sandy),medium (loamy),hard (clay) soil. It is not necessary for the soil to be well drained.
The soil prefers the following PH / acid levels :
- pH of less than 6, Acidic soils
- pH between 6 and 8, Neutral soils
- pH greater than 8, Basic soils
Giant Ragweed prefers moist soils

Ideal Planting Locations

Giant Ragweed can grow in semi or areas with no shade.

Alluvial waste places, sometimes forming vast pure stands[222].

Planting places suited to this plant described below.

• Grows within a woodland garden
• Can be planted in Cultivated Beds

Cultivation Details

We have very little information on this species but suggest growing it in a sunny position in a well-drained soil[K]. This plant is sometimes cultivated by the N. American Indians for food and medicine[207].

Edible Uses*

* See disclaimer
Edible Rating: 2/5
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[207]. The following report is for A. artemesifolia, it quite possibly also applies to this species[K]. An oil is obtained from the seed. It has been suggested for edible purposes because it contains little linolenic acid[61, 183]. The seed contains up to 19% oil[61], it has slightly better drying properties than soya bean oil[183].

• Oil -

Medicinal Uses*

* See disclaimer
Medicinal Rating: 3/5
The leaves are very astringent, emetic and febrifuge[222, 257]. 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[222]. The juice of wilted leaves is disinfectant and is applied to infected toes[257]. A tea made from the roots is used in the treatment of menstrual disorders and stroke[222]. The pollen is harvested commercially and manufactured into pharmaceutical preparations for the treatment of allergies to the plant[222].

• Antidote - Counters poisoning.
• Astringent - Produces contraction in living tissue, reducing the flow of secretions and discharges of blood, mucus, diarrhoea etc.
• Emetic - Induces vomiting.
• Poultice - A moist, usually warm or hot, mass of plant material applied to the skin in the treatment of burns etc.
• Skin - Plants used in miscellaneous treatments for the skin.
• Women's complaints - A very vague title, it deals with a miscellany of problems peculiar to the female sex.

Propagation

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

Known Hazards

The pollen of this plant is a major cause of hayfever in N. America[222]. Ingesting or touching the plant can cause allergic reactions in some people[222].

Other Uses

A red colour is obtained from the crushed heads[207]. (This probably refers to the seed heads[K].) The sap of the plant can stain the skin red[274].

• Dye - Plants that provide dyes.

Cultivars

no recorded cultivars

References

A Field Guide to Medicinal Plants. Eastern and Central N. America.
Foster. S. & Duke. J. A.
Author: Foster. S. & Duke. J. A.
Rating:
Publisher : A concise book dealing with almost 500 species. A line drawing of each plant is included plus colour photographs of about 100 species. Very good as a field guide, it only gives brief details about the plants medicinal properties.
Date of Publication : 1990

An Illustrated Flora of the Northern United States and Canada
Britton. N. L. Brown. A.
Author: Britton. N. L. Brown. A.
Rating:
Publisher : Reprint of a 1913 Flora, but still a very useful book.
Date of Publication : 1970

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