Giant Ragweed, Great ragweed, Texan great ragweed, Bitterweed, Bloodweed, Buffalo Weed, Horse Cane
Ambrosia trifida
Family: Asteraceae or Compositae
What it is like
An erect summer annual with some useful medicinal qualities and minor edible and other uses. Bloom Color: Green. Main Bloom Time: Early fall, Late summer, Mid summer. Form: Upright or erect. Common Names include: great ragweed, Texan great ragweed, giant ragweed, tall ragweed, blood ragweed, perennial ragweed, horseweed, buffaloweed, and kinghead. Spanish: Artemisa grande. Germany: Dreilappige Ambrosie; Dreispaltige Ambrosie. Japan: kuwamodoki; oobutakusa. Netherlands: driedeelige Ambrosia. Sweden: tall Ambrosia. USA: bitterweed; buffalo weed; crown-weed; horse-cane; horse-weed; kinghead; tall ragweed.
Ambrosia trifida is a ANNUAL growing to 2 m (6ft 7in) at a medium rate. It is in flower from August to October. The species is monoecious (individual flowers are either male or female, but both sexes can be found on the same plant) and is pollinated by Wind. Suitable for: light (sandy), medium (loamy) and heavy (clay) soils. Suitable pH: mildly acid, neutral and basic (mildly alkaline) soils. It can grow in semi-shade (light woodland) or no shade. It prefers moist soil.
Height (m): 2
Where it is found
Alluvial waste places, sometimes forming vast pure stands.
Eastern N. America - Quebec to Florida, west to Manitoba, Colorado and Mexico.
Conservation Status: This taxon has not yet been assessed.
Countries/locations it is found in
How it is used
Food
Rating: 1
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.
Oil: Oil
Medicine
Rating: 3
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.
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.
Other
Rating: 1
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. A positive impact may be seen with a noted decrease in the numbers of plant-parasitic nematodes found in soyabean fields where A. trifida is present (Wang et al., 1998).
Dye: Plants that provide dyes.
Oil: Vegetable oils have many uses, as lubricants, lighting, soap and paint making, waterproofing etc. This does not include the edible oils unless they are also mentioned as having other uses.
How it is grown
We have very little information on this species but suggest growing it in a sunny position in a well-drained soil. This plant is sometimes cultivated by the N. American Indians for food and medicine. Special Features: North American native, Invasive, Inconspicuous flowers or blooms.
Propagating it: Seed - we have no details for this species but suggest sowing the seed in situ in April.
Best place to grow: Woodland Garden Cultivated Beds;
Habit: Annual
Hardiness: 1-11
Growth: Medium
Soil: Light (sandy), medium, heavy (clay)
Shade: Semi-shade, no shade
Moisture: Moist
Things to keep in mind
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.
A noxious weed, both in its native range and in areas where it is an introduced and often invasive species. Extremely competitive and is very difficult to control, especially in many broadleaved crops. a declared noxious weed in California, Delaware, Illinois and New Jersey, USA and a quarantine weed in Poland and Russia.