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oriental lady's thumb (Polygonum cespitosum var. longisetum)
COMMON NAMES:
oriental lady's thumb
Asiatic smartweed
Asiatic waterpepper
bristled knotweed
bunchy knotweed
bristly lady's-thumb
long-bristled smartweed
tufted knotweed
SCIENTIFIC SYNONYMS:
Persicaria caespitosa var. longiseta (Bruijn) C. F. Reed
Polygonum caespitosum Blume
Polygonum caespitosum var. longisetum (Bruijn) Steward
Polygonum cespitosum Blume
Polygonum cespitosum var. longisetum (Bruijn)
Polygonum longisetum Bruijn
TAXONOMY: The currently accepted scientific name for orietal lady's thumb is Polygonum cespitosum Blume var. longisetum (Bruijn) A.N. Steward. Thi species is listed as Persicaria longisetum in the Flora of Virginia.
NATIVE STATUS: Introduced, United States and Canada.
GENERAL BOTANICAL CHARACTERISTICS:
Habit: Stems are prostrate or erect, and can reach 3.2 feet (1 m) in height.
Leaves: Leaves are alternate, thin, and lanceolate to elliptic in shape, 0.75 to 3 inches (2-7.5 cm) in length.
Flowers: Flowers are small, dark pink, and arranged in few to many thin spikes.
Fruit/Seed: Seeds are small, smooth, trigonous achenes.
Roots: Oriental lady's thumb has fibrous roots and a shallow taproot. It has been reported that Oriental lady's thumb may root from lower nodes. Rhizomes and stolons are absent.
REGENERATION PROCESS: Oriental lady's thumb reproduces by seed and does not regenerate vegetatively.
HABITAT TYPES: Oriental lady's thumb occurs on a variety of sites, including wetlands and riparian or floodplain, bottomland, and upland forests. Floras report Oriental lady's thumb in disturbed areas, including roadsides, along railroads, and in "waste" areas. It also occurs along trails and in fallow fields, hedgerows, lawns, gardens, and old home sites.
SITE CHARACTERISTICS: Oriental lady's thumb shows no clear preference for light. Oriental lady's thumb occurs on moist soil, though it is occasionally reported in dry areas. Oriental lady's thumb plants produce the longest roots when exposed to constant moisture, and roots were shortest when exposed to dry or flooded conditions. Oriental lady's thumb is often associated with sandy soil, including soils dominated by sand, deep sandy soils, and course sandy soils.
SEASONAL DEVELOPMENT: Oriental lady's thumb flowers from May to October.
GENERAL DISTRIBUTION: Oriental lady's thumb occurs from Florida to Maine and westward to Texas and New Mexico, Kansas and
Nebrska (not including Oklahoma), Iowa and Minnesota. It also occurs in Quebec and Ontario, and then in the far western provinces of Alberta and British Columbia.
SKY MEADOWS DISTRIBUTION: To be determined.
IMPORTANCE AND USES: Oriental lady's thumb is mildly toxic and has few natural predators; however, Oriental lady's thumb may be eaten by some wildlife and has been planted in some areas for that purpose. Oriental lady's thumb seeds have been reported germinating from white-tailed deer pellets, suggesting that plants are consumed by some animals.
