Common Name: Roman Wormwood

General Information

Ambrosia artemisiifolia is an erect, much-branched annual plant usually growing 10 - 60cm tall, exceptionally to 150cm or even more[, ].
The plant is harvested from the wild for local use as a medicine - the plant is sometimes also cultivated for medicinal use[].. A good quality oil can be obtained from the seeds - the plant has been suggested for commercial cultivation as a source of this oil[].
The plant establishes easily and in high abundance in human impacted and disturbed areas, invading roadsides, wastelands and poor or overgrazed pastures. It is considered an invasive species in Europe, parts of Asia and Australia, although it is not an extremely competitively aggressive species and is mainly considered a noxious weed that interferes with other cultivated crops. The main impact of this plant is the copious amount of pollen produced from male flowers that are allergens to sensitive people, compounding health problems like rhinitis, oculorhinitis, asthma and causing skin irritations[, ].

Known Hazards

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[].

Botanical References

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Range

N. America - Alaska to Labrador, south to California and Florida.

Habitat

Waste places in Western N. America[]. Found in dry soils, it can become a pernicious weed in cultivated soils[]. Wet to dry soils, disturbed sites; at elevations from sea level to 1,000 metres or more[].

Properties

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

Cultivation Details

Prefers a warm position in full sun[]. Grows best in a humus-rich, nutrient rich, slightly acidic soil[]. Tolerant of dry soils[].
Some plants produce mainly sterile heads[].
Hybrids between Ambrosia artemisiifolia and Ambrosia psilostachya have been called Ambrosia × intergradiens W. H. Wagner. The name Ambrosia × helenae Rouleau applies to hybrids between Ambrosia artemisiifolia and Ambrosia trifida[].

Edible Uses

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[].

Medicinal

The leaves are very astringent, emetic and febrifuge[, ]. They are taken as a tea in the treatment of fevers, pneumonia, nausea, intestinal cramps, diarrhoea and mucous discharges[, ].
The leaves are applied externally to insect bites, rheumatic joints and various skin complaints[, ].
Juice from the wilted leaves is disinfectant and is applied to infected toes[].

An essential oil obtained from the plant acts as an antimicrobial, having antibacterial and antifungal compounds[].

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[].

Other Uses

None known

Propagation

Seed - in nature the seed ripens in the autumn and then enters a dormancy period that requires a cold stratification in order to germinate. Germination occurs in the spring with only a portion of the seed bank germinating while the rest of the seeds enter a secondary dormancy period. The secondary dormancy of the seed makes this species well adapted at surviving in continuously disturbed sites. Seeds have been known to remain viable after 20 years of burial with 85% germination rate[].