spotted ladysthumb
Family
PolygonaceaeScientific Name
Polygonum persicaria
Other Common Names:
lady's thumb
smart weed
pondshore knotweed
lady's thumb smartweed
Synonyms (former Scientific Names):
Persicaria ruderalis
Polygonum persicaria var. ruderale
Persicaria maculosa
Persicaria vulgaris
Persicaria maculata
Polygonum minus
Polygonum puritanorum
Persicaria persicaria
Polygonum fusiforme
Polygonum dubium
Polygonum persicaria var. angustifolium
Habit
This erect summer annual flowers from July to October. It can grow up to 3 1/2 feet in height with numerous branches.
Leaves
The alternately arranged leaves are lance to egg shaped, and grow from 2 to 6 inches long and can be up to 2 inches wide. The leaves have a hairy upper surface, and margins, while the lower surface remains smooth. The leaves often have a purple mark in the center, resembling a lady's thumb.
Identifying Characteristics
A membranous sheath or ocrea surrounds the base of each petiole. This species has stiff hairs arising from the top of each ocrea.
Flower Seed Head
The pink or white flowers are usually grouped in terminal spikes on the ends of long, hairy stems.
Seed Fruit
Each seed is enclosed in an achene. The achenes are a glossy black, and are circular to oval, 2.5 to 3.5 mm wide.
Where Found
This plant prefers moist soil.
Growth Habit
upright and nonwoody
Thorns or Spines
not present
Approximate Flower Diameter
pencil
Dominant Flower Color
red
Flower Symmetry
radial symmetery
Leaf Hairs
has hairs
Leaf Shape
lance
Leaf Arrangement
alternate
Leaf Margin
entire
Leaf Structure
simple
Leaf Stalk
shorter than leaf
Stem Hairs
has hairs
Stem Cross Section
round or oval
Milky Sap
not present
Root Structure
Varies:
fibrous,
taproot
Life Cycle
summer annual
Ochrea
present
Plant Type
Herb