Common Ragweed, Annual Ragweed, Hay-fever Weed
Kingdom: Plantae, Division: Angiosperms, Class: Eudicots, Order: Asterales, Family: Asteraceae, Genus: Ambrosia, Species: Ambrosia artemisiifolia · Asteraceae (Daisy/Sunflower family) · Compound-like (deeply pinnatifid/bipinnatifid), Deciduous herbaceous annual
Species
Ambrosia artemisiifolia (Confidence Level: 95%)
Leaf Type
Compound-like (deeply pinnatifid/bipinnatifid), Deciduous herbaceous annual
Family
Asteraceae (Daisy/Sunflower family)
Shape
Overall ovate-deltoid outline, deeply divided into multiple lobes (pinnately lobed or dissected)
Size
Approximately 2 to 4 inches in length and 1.5 to 2.5 inches in width; typical for a young seedling of this species.
Margin
Deeply lobed to pinnatifid; the lobes themselves may have smaller teeth or further divisions.
Arrangement
Opposite on the lower portions of the stem, becoming alternate further up the plant as it matures.
Rarity
Very Common; frequently considered a noxious weed due to its prolific seed production and allergenic pollen.
Color & Pattern
Uniform bright green on the upper surface, slightly paler green on the underside. No variegation; some slight light-colored stippling likely from minor environmental stress or early insect activity.
Venation Pattern
Pinnate midribs on each lobe; secondary veins are less prominent but create a net-like appearance within lobes.
Texture & Surface
Relatively smooth (glabrous) to the eye but often possesses fine, sparse hairs (pubescent) on the underside and along the stems.
Description
An upright annual herb that can reach 3-6 feet. It features fern-like foliage and produces inconspicuous green flowering spikes that release massive amounts of wind-borne pollen in late summer and autumn.
Key Features
Fern-like, deeply dissected leaves; hairy stems; lack of aromatic scent when crushed (unlike similar-looking Mugwort or Marigolds).
Habitat
Disturbed soils, roadsides, agricultural fields, vacant lots, and garden beds; thrives in full sun and various soil types.
Geographic Range
Native to North America; now a widespread invasive or naturalized species across Europe, Asia, and South America.
Condition Notes
Good health; showing vigorous new growth. Minor white stippling suggests possible early leafhopper or mite feeding, but the plant is overall robust.
Interesting Facts
A single plant can produce up to a billion grains of pollen per season and 30,000 to 60,000 seeds that can remain viable in the soil for decades.
Medicinal & Uses
Historically used by some Native American tribes for topical skin treatments (astringent), but primarily known today as a major allergen causing hay fever.
Ecological Role
Provides seeds for various songbirds and upland game birds; however, it is largely viewed as a nuisance in agricultural and human-populated areas.
Similar Species
Artemisia vulgaris (Mugwort) - has silver-white undersides; Marigolds (Tagetes) - have a very strong scent and darker foliage; Poison Hemlock - has hairless, purple-spotted stems.
Foraging Tips
Look for it in disturbed garden soil and sunny waste areas; verify by the lack of scent and the distinct feather-like leaf structure without silver undersides.
Toxicity Warning
Non-toxic to touch or ingestion in small amounts, but highly allergenic via inhalation. May cause contact dermatitis in sensitive individuals. Toxicity Level: Low (High Allergenicity).