prostrate knotweed
Family
PolygonaceaeScientific Name
Polygonum aviculareSynonyms (former Scientific Names):
Polygonum aviculare var. vegetum
Polygonum monspeliense
Polygonum heterophyllum
Habit
Emerges in the early spring, but can continue to emerge in the late spring and summer as well. Flowering occurs from June through November.
Leaves
Leaves begin looking almost grass-like and have a waxy whitish coating. Mature leaves are broad leaves that are narrowed at the base, ranging from lanceolate, elliptic to oblong shapes. The petioles are short and have a conspicuous ocrea sheathing the stem at the leaf base.
Identifying Characteristics
The plant forms mats or clusters of dead mesh-like stems that remain throughout the winter.
Flower Seed Head
Flowers appear in 1 to 5 axillary clusters. They are small white to green with some pinkish margins, lacking petals.
Seed Fruit
The friut contains the seed (achene). Achense are about 2 to 3 mm long teardrop-shaped with dark reddish brown to black coloring.
Where Found
Prostrate knotweed can infest turfgrass, nursery crops, landscapes, and areas that is damaged by traffic such as pathways. Grows well in stressed areas.
Dominant Flower Color
Varies:
white,
pink
Leaf Hairs
no hairs
Leaf Shape
oval
Leaf Arrangement
alternate
Leaf Stalk
shorter than leaf
Stem Cross Section
round or oval
Milky Sap
not present
Root Structure
taproot
Life Cycle
summer annual
Ochrea
present
Plant Type
Herb