lanceleaf ragweed

Family

Asteraceae

Scientific Name

Ambrosia bidentata

Other Common Names:

southern ragweed

Habit

Branching annual

Leaves

Leaves are opposite below and alternate above; have a lanceolate shape with no lobes and no leaf stalk. Often, the leaves will have one pair of large teeth on the lower half of the leaf. Leaves are densely hairy mostly on the underside. The upper side of the leaf may be hairless.

Identifying Characteristics

This is an annual weed that is highly branching and can grow up to 3 ft tall. Both the stem and leaves are densely covered in long, straight (not woolly) hairs. Often, the leaves will have one pair of large teeth on the half of the leaf nearest to the stem; otherwise, the leaves may be finely toothed or may not have any teeth at all.

Flower Seed Head

Flowers are non-showy. The inflorescence is a tall, ascending spike.

Seed Fruit

Hairy bur. Fruit has several short stiff spines and is beaked at one end.

Where Found

Commonly found in prairies and waste areas

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

lance

Leaf Arrangement

Varies:

alternate,

opposite

Leaf Margin

Varies:

entire,

serrated

Leaf Structure

simple

Leaf Stalk

none

Stem Hairs

has 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