common ragweed
Family
AsteraceaeScientific Name
Ambrosia artemisiifolia
Other Common Names:
annual ragweed
Habit
This erect summer annual flowers from August through October, spreading allergy-causing pollen in the air.
Leaves
The 4 to 10 cm long leaves are hairy, and are generally egg shaped once or twice compound. The leaves are alternate, although the lower leaves are occasionally opposite. The hairy stem can be green to pinkish red.
Identifying Characteristics
This plant can be identified by the purple color found on the undersides of its cotyledons. It is similar to giant ragweed, just smaller.
Flower Seed Head
The flowers occur in small clusters on terminal branches. Male and female flowers occur in different parts of the plant, with male flowers occurring in long, slender racemes, and females at the leaf axils.
Seed Fruit
A single seed forms in each 3 to 4 mm long achene. The achenes have longitudinal ridges that terminate in short spikes. The achenes have been known to survive for over 80 years in the soil.
Where Found
This plant prefers full sun, and slightly dry conditions. It can be found growing in disturbed areas such as fields, pastures, and roadsides.
Growth Habit
upright and nonwoody
Thorns or Spines
not present
Approximate Flower Diameter
pencil
Dominant Flower Color
Varies:
yellow,
green
Flower Symmetry
not symmetrical
Leaf Hairs
has hairs
Leaf Shape
Varies:
oval,
triangle
Leaf Arrangement
Varies:
alternate,
opposite
Leaf Margin
lobed
Leaf Structure
pinnate
Leaf Stalk
Varies:
shorter than leaf,
longer than leaf
Stem Hairs
Varies:
has hairs,
no hairs
Stem Cross Section
round or oval
Milky Sap
not present
Root Structure
Varies:
fibrous,
taproot
Life Cycle
summer annual
Ochrea
not present
Plant Type
Herb