Knotgrass Polygonum aviculare
- Phonetic Spelling
- po-LI-go-num a-vik-yoo-LAIR-ee
- Description
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Prostrate knotweed is a prostrate, summer annual or perennial weed in the buckwheat family and originally from Eurasia. It grows in fields and wetlands, in both high and low elevations, throughout the world and in all 50 states of the United States. Each plant is capable of producing thousands of seeds that stay viable for several years. The plant grows low to the ground on long stems up to 3 feet long and mowing is ineffective as a control. The foliage is often a blue green and small flowers, that only open in hot, sunny weather, occur at the base of each leaf. The genus name is Greek for "many knees", in reference to the prominent nodes along the stem. The species name means "little bird" because the fruits resemble a bird's beak.
Prostrate Knotweed prefers full sun and moist to dry, heavy soil. It does well in poor soil, including heavily contaminated ones. It tolerates a fair amount of trampling.
The plant has a slender shallow taproot that frequently branches and the plant spreads by reseeding itself.
Diseases, Insect Pests, and Other Plant Problems:
Prostrate Knotweed can be a problem for grain and crop fields, lawns and cities where it grows in the cracks of pavement and along roads.
- See this plant in the following landscape:
- Cultivars / Varieties:
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- Tags:
- Cultivars / Varieties:
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- Tags:
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Attributes:
- Genus:
- Polygonum
- Species:
- aviculare
- Family:
- Polygonaceae
- Uses (Ethnobotany):
- Parts of the plant used medicinally and the leaves are sometimes used to produce blue or green dye.
- Life Cycle:
- Annual
- Perennial
- Recommended Propagation Strategy:
- Division
- Seed
- Country Or Region Of Origin:
- Macaronesia and Eurasia
- Distribution:
- Temperate regions worldwide.
- Wildlife Value:
- Food plant for caterpillars.
- Edibility:
- Seeds edible raw or ground into a flour
- Dimensions:
- Height: 0 ft. 3 in. - 0 ft. 8 in.
- Width: 2 ft. 0 in. - 3 ft. 0 in.
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Whole Plant Traits:
- Plant Type:
- Annual
- Perennial
- Weed
- Woody Plant Leaf Characteristics:
- Broadleaf Evergreen
- Habit/Form:
- Prostrate
- Spreading
- Growth Rate:
- Slow
- Maintenance:
- High
- Texture:
- Coarse
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Cultural Conditions:
- Light:
- Full sun (6 or more hours of direct sunlight a day)
- Partial Shade (Direct sunlight only part of the day, 2-6 hours)
- Soil Texture:
- Clay
- Sand
- Shallow Rocky
- Soil pH:
- Acid (<6.0)
- Alkaline (>8.0)
- Neutral (6.0-8.0)
- Soil Drainage:
- Good Drainage
- Moist
- Occasionally Dry
- NC Region:
- Coastal
- Mountains
- Piedmont
- USDA Plant Hardiness Zone:
- 2a, 2b, 3a, 3b, 4a, 4b, 5a, 5b, 6a, 6b, 7a, 7b, 8a, 8b, 9a, 9b, 10a, 10b
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Fruit:
- Fruit Color:
- Brown/Copper
- Display/Harvest Time:
- Fall
- Summer
- Fruit Type:
- Achene
- Fruit Length:
- < 1 inch
- Fruit Width:
- < 1 inch
- Fruit Description:
- A 3-angled brown achene develops within the sepals of each flower. This achene tapers at one end and a fine membrane often clings to the surface.
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Flowers:
- Flower Color:
- Pink
- White
- Flower Inflorescence:
- Cyme
- Flower Bloom Time:
- Fall
- Summer
- Flower Shape:
- Radial
- Tubular
- Flower Petals:
- Colored Sepals
- Flower Size:
- < 1 inch
- Flower Description:
- A small cluster of 1 to 5 tiny flowers appear in the axil of leaves near the stem end mid-summer to early fall. Each tiny flower consists of 5 sepals, several stamens, and no petals. The flat sepals have white margins, otherwise they are green, pink, or purple. The flowers bloom from mid-summer to early fall for 2 to 3 months, but open for a short period when the weather is hot and sunny.
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Leaves:
- Woody Plant Leaf Characteristics:
- Broadleaf Evergreen
- Leaf Color:
- Blue
- Green
- Leaf Feel:
- Smooth
- Leaf Type:
- Simple
- Leaf Arrangement:
- Alternate
- Leaf Shape:
- Elliptical
- Lanceolate
- Oblong
- Obovate
- Spatulate
- Leaf Margin:
- Entire
- Hairs Present:
- No
- Leaf Length:
- < 1 inch
- Leaf Width:
- < 1 inch
- Leaf Description:
- One inch by 1/3 inch oblong green to blue-green, smooth, alternate leaves with entire margins. A membranous sheath (ochrea) wraps around the stem at the base of each leaf.
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Stem:
- Stem Color:
- Green
- Stem Is Aromatic:
- No
- Stem Form:
- Zig Zags
- Stem Surface:
- Smooth (glabrous)
- Stem Description:
- Stem is wiry, matted, branching, and prostrate to erect.
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Landscape:
- Resistance To Challenges:
- Compaction
- Dry Soil
- Foot Traffic
- Poor Soil
- Problems:
- Weedy
