curlytop knotweed
Family
PolygonaceaeScientific Name
Polygonum lapathifolium
Other Common Names:
curltop ladysthumb
pale smartweed
Synonyms (former Scientific Names):
Polygonum oneilli
Polygonum tomentosum
Polygonum incanum
Polygonum incarnatum
Polygonum pensylvanicum
Polygonum scabrum
Persicaria incarnata
Persicaria tomentosa
Persicaria lapathifolia
Polygonum nodosum
Habit
This erect summer annual can grow from 3 to 5 feet tall, and can be found flowering from June through October.
Leaves
The leaves are generally lance shaped with smooth margins. The whitish undersides have minute sunken glands, while the upper surface remains smooth. Stems are connected to the stalk by thick sheaths.
Identifying Characteristics
Pale smartweed is very similar to Lady's Thumb, but can be distinguished by the hair on the lower surfaces of its leaves, and by the lack of hairs on the upper edge of the leaf sheaths.
Flower Seed Head
The white to pale pink flowers can be found on 1 to 3 inch long stalks in dense, hanging spikes. Each 5-petaled flower never opens, and is insect or self pollinated.
Seed Fruit
The seeds develop in an ovate, flattened achene that is slightly concave on either side. Each achene can grow up to 2 mm in length. The individual seeds are shiny, lens shaped, and black.
Where Found
Pale smartweed prefers loose, rich, acidic soils high in organic matter. It can be found in wet environments such as areas near ponds, streams, wet fields, and waste places.
Growth Habit
upright and nonwoody
Thorns or Spines
not present
Approximate Flower Diameter
pencil
Dominant Flower Color
Varies:
white,
purple,
pink
Leaf Hairs
has hairs
Leaf Shape
lance
Leaf Arrangement
alternate
Leaf Margin
entire
Leaf Structure
simple
Leaf Stalk
shorter than leaf
Stem Hairs
Varies:
has hairs,
no hairs
Stem Cross Section
round or oval
Root Structure
fibrous
Life Cycle
summer annual
Ochrea
present
Plant Type
Herb