Roman Wormwood, Bitterweed, Blackweed, Carrot Weed, Hay Fever Weed, Stickeweed, Tassel Weed, Wild Ta
Ambrosia artemesiifolia

Family: Asteraceae or Compositae

What it is like

Bloom Color: Green. Main Bloom Time: Early fall, Late summer, Mid summer, Mid fall. Form: Upright or erect. Other Names: Annual Ragweed, Bitterweed, Blackweed, Carrot Weed, Hay Fever Weed, Roman Wormwood, Stammerwort, Stickweed, Tassel Weed, Wild Tansy, and American Wormwood.

Ambrosia artemesiifolia is a ANNUAL growing to 0.9 m (3ft) by 0.2 m (0ft 8in) at a medium rate. See above for USDA hardiness. It is hardy to UK zone 4. 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): 0.9

Where it is found

Waste places in Western N. America. Found in dry soils, it can become a pernicious weed in cultivated soils.

N. America - British Columbia to Nova Scotia and Florida. Locally established casual in Britain.

Conservation Status: This taxon has not yet been assessed.

Countries/locations it is found in

How it is used

Food

Rating: 2

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, rheumatic joints and various skin complaints, internally they are used as a tea in the treatment of fevers, pneumonia, nausea, intestinal cramps, diarrhoea and mucous discharges. Juice from the 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.

Disinfectant: Used for cleaning wounds.

Emetic: Induces vomiting.

Febrifuge: Reduces fevers.

Women's complaints: A very vague title, it deals with a miscellany of problems peculiar to the female sex.

Other

Rating: 1

There is some indication it has been used as a disinfectant and Oil.

Disinfectant: Plants used for disinfecting.

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. It has been suggested for commercial cultivation. Some plants produce mainly sterile heads. The pollen from the flowers of this species is an important cause of hay-fever in N. America. 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: 4-8

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.

It is listed as a noxious weed in Illinois (common ragweed) and Oregon (ragweed)as a "B" designated weed. Ragweed is a very competitive weed and can produce yield losses in soybeans as high as 30%. Control with night tillage reduces emergence by around 45%. Small grains in rotation will also suppress common ragweed if they are overseeded with clover. Otherwise, the ragweed will grow and mature and produce seed in the small grain stubble.

Its other names

Local names

Synonyms

A. elatior.