Common Ragweed (also known as Annual Ragweed, Bitterweed, Roman Wormwood)
Kingdom: Plantae, Division: Tracheophyta, Class: Magnoliopsida, Order: Asterales, Family: Asteraceae, Genus: Ambrosia, Species: Ambrosia artemisiifolia · Asteraceae (Daisy, Aster, or Sunflower family) · Pinnately or bipinnately compound to deeply lobed simple leaves, deciduous
Species
Ambrosia artemisiifolia
Leaf Type
Pinnately or bipinnately compound to deeply lobed simple leaves, deciduous
Family
Asteraceae (Daisy, Aster, or Sunflower family)
Shape
Deeply lobed and divided, lanceolate in overall outline, giving a fern-like or finely cut appearance
Size
Approximately 2 to 4 inches long and 1 to 2 inches wide, which is typical for mature leaves on this plant
Margin
Deeply lobed with coarsely toothed or serrated margins on the individual segments
Arrangement
Opposite on the lower stem and becoming alternate higher up on the plant
Rarity
Very Common, often considered a nuisance weed
Color & Pattern
Vibrant medium to dark green on the upper surface, slightly paler green on the underside; covered in fine, whitish hairs, giving it a slightly frosted or pubescent look
Venation Pattern
Pinnate venation with a prominent central midrib and sub-veins extending into each lobe
Texture & Surface
Pubescent (hairy) and slightly rough to the touch on both the upper and lower surfaces
Description
Common Ragweed is an annual herbaceous plant known primarily for its inconspicuous flowers and highly allergenic pollen. It typically grows as a branching, erect plant reaching heights of 1 to 4 feet. The stems are rough and hairy. While its fern-like foliage is quite attractive, the plant is universally disliked during late summer and autumn due to its prolific production of wind-borne pollen, which is a primary trigger for seasonal allergic rhinitis (hay fever).
Key Features
Deeply divided, fern-like, opposite leaves on the lower stem, hairy stems, and lack of showy flower petals, producing small green flower spikes that release massive amounts of pollen
Habitat
Disturbed soils, agricultural fields, roadside edges, vacant lots, and waste areas; thrives in full sun and well-drained soils
Geographic Range
Native to North America, now widespread across much of North America and introduced as an invasive weed in parts of Europe and Asia
Condition Notes
The leaf appears healthy, vibrant green, fully mature, and undamaged by pests or disease, receiving an overall health grade of Excellent
Interesting Facts
Despite being infamous for causing hay fever, ragweed is a native plant that provides critical late-season food sources and seeds for various birds and small mammals. The genus name Ambrosia means food of the gods
Medicinal & Uses
Has historically been used in some Indigenous herbal remedies for staunching bleeding or soothing skin irritation, but modern use is virtually non-existent due to its extreme allergenicity and potential toxicity in large amounts
Ecological Role
Acts as an early successional colonizer of bare or disturbed soil, helping to stabilize ground and prevent erosion while providing seeds for overwintering birds
Similar Species
Giant Ragweed (Ambrosia trifida), which features much larger leaves with three to five lobes; and various members of the carrot family or mugwort (Artemisia vulgaris), which can be distinguished by smell and flower structure
Foraging Tips
Look for disturbed soils along trails and roadsides during spring and summer; leaves can be identified by their fern-like, opposite arrangement and hairy texture, though harvesting is generally discouraged due to allergy concerns
Toxicity Warning
Non-toxic to touch, but the pollen is a severe allergen causing hay fever. The plant contains bitter sesquiterpene lactones which can cause contact dermatitis in sensitive individuals and can be toxic to livestock if ingested in large quantities