woolly burdock
Family
AsteraceaeScientific Name
Arctium tomentosumHabit
These robust plants grow to 3 m in height and are umbrella-shaped with flower heads at the tips of the branches. It produces a large fleshy tap root during the first year of life. Stems are red and green striped.
Leaves
The first year of growth is a basal rosette. The leaves of the rosette are usually 45 cm long by 40 cm wide and are white and woolly beneath. The mature plants leaves are alternate and smaller in size toward the top of the plant. Leaves are ovate with a heart-shaped base.
Identifying Characteristics
Floral bracts are covered with soft hairs that spread at maturity (florets have sticky hairs). The hooked bristles on the floral bracts aid in the dispersal of seeds.
Flower Seed Head
Flowers can be found at the ends of branches in rounded or flat toped clusters. The clusters, 3 - 4.5 cm across, consist of purple disk florets surrounded by overlapping hooked bracts (like velcro).
Seed Fruit
An achene containing a single seed is approximately 6mm long. The seed a mottled brown club-shape is 5-6.5 mm long with barbed yellow bristles. Plants are capable of producing 12,000 seeds that remain viable for up to 3 years.
Where Found
This plant is often found in fence lines, waste areas, and stream banks throughout Canada and the northern two-thirds of the United States.
Growth Habit
upright and nonwoody
Thorns or Spines
not present
Approximate Flower Diameter
Varies:
nickle,
quarter,
half dollar
Dominant Flower Color
Varies:
white,
purple,
pink
Flower Symmetry
radial symmetery
Leaf Hairs
has hairs
Leaf Shape
oval
Leaf Arrangement
alternate
Leaf Margin
serrated
Leaf Structure
simple
Leaf Stalk
shorter than leaf
Stem Hairs
has hairs
Stem Cross Section
round or oval
Milky Sap
not present
Root Structure
taproot
Life Cycle
biennial
Ochrea
not present
Plant Type
Herb