Ambrosia artemisiifolia (Common Ragweed)


Botanical Information

FamilyAsteraceae
GenusAmbrosia
Speciesartemisiifolia
CategoryWildflowers & Weeds
OriginNative to North America.
Ethnobotanical Uses
Disclaimer
Native Americans used this as a herbal medicine, both externally and internally. Major cause of hay fever, an allergic reaction to its wind-borne pollen during, the late summer and early autumn. Today the pollen is harvested commercially for use in pharmaceuticals designed to treat hay fever.

Details

USDA Hardiness Ref.
Canada Hardiness Ref.
RHS Hardiness ZoneH7
RHS Hardiness Ref.
Height3 m
GrowthFast
Flowering PeriodJune, July

Description and Growing Information

ShapeWidespread.
PropagationSeed.
CultivationFull sun. Will thrive in clay, gravel or sand but prefers sterile soil. Drought resistant.
PestsRagweed, caterpillars and moths.
HabitatWeedy meadows and cropland.
Flower/Leaf Bud DescriptionSeeds are produced which can remain viable for 5 years or more.
Leaf DescriptionHairy stems. The leaves are 15 cm long, 10 cm wide and opposite or alternate along the stem. Deeply pinnatifid, broadly lanceolate and much wider at the base than the tip. Small emergent leaves often have hairs on their underside.
Flower DescriptionSmall flowers that matures into achenes. Each flower is about 3 mm long. Male flowers produce pollen. Many of the upper stems terminate in one or more cylindrical spikes of flowers that are half as long as the leaves.
Colour DescriptionThe stem is a green to light pinkish-red colour. The small flowers are initially green but turn a yellowish-green or brown as it matures.
Texture DescriptionRoot system is fibrous.

Photographs