This spiny, weedy plant grows in clumps of many erect stems.
The involucres (whorl of bracts) of staminate heads (flowers have stamens but not pistels) usually each with 1 to 5+ black nerves. The fruit burs are spindle to inversely pyramidal in shape. Leaf blades are mostly 1 to 2 pinnately lobed.
Habitat
It is adaptable and grows well in disturbed areas, easily becoming weedy.
Flower Characteristics
There are many tiny greenish flower heads along the stems, facing downward. Male flowers are in separate flower heads that are above the female flower heads., female flowers lack petals (corollas).
Leaf and Stem Characteristics
Opposite below, alternate above; simple; lobed bipinnatifid to pinnatifid; blades 1/3 inch to 3-3/4 inches long, 1/4 to 3 inches wide.
Fruit and Seed Characteristics
1 seeded with hard shell covered with curved spines.