Russian Knapweed Rhaponticum repens
Other Common Name(s):
Previously known as:
- Acroptilon repens
- Centaurea repens
- Phonetic Spelling
- ra-PON-ti-kum REE-penz
- Description
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Russian Knapweed is a flowering, bushy perennial weed in the daisy family and native to Eastern Europe, Mongolia, and the Himalayas. The plant has deep roots and a reputation for long life (some stands are reported to have been in existence for 75 years). The roots spread and the plant will form dense colonies. The leaves and stems are initially covered in long, fine hairs, but become smooth with age. Pink to purple flowers appear in spring and last through summer.
Russian Knapweed is considered a serious weed pest in the western United States. It reproduces both by seeds and by adventitious buds on deep, spreading roots forming dense colonies and is difficult to control or eradicate once it becomes established. It is poisonous to horses.
Disease, Insect Pests, and Other Plant Problems:
No known diseases or insect pests. Russian Knapweed is persistent and difficult and expensive to control, is toxic to horses and out competes native vegetation. It is listed by western states as a noxious weed, to be suppressed, contained, or locally extirpated.
- 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:
- Rhaponticum
- Species:
- repens
- Family:
- Asteraceae
- Life Cycle:
- Perennial
- Recommended Propagation Strategy:
- Seed
- Country Or Region Of Origin:
- Eastern Europe to Mongolia
- Distribution:
- Introduced to Northern Europe, most of the United States (except the Southeast), Canada, Australia, and South Africa.
- Edibility:
- Can be poisonous to horses.
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Whole Plant Traits:
- Plant Type:
- Perennial
- Weed
- Habit/Form:
- Dense
- Rounded
- Spreading
- Growth Rate:
- Rapid
- Maintenance:
- High
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Fruit:
- Fruit Color:
- Cream/Tan
- Display/Harvest Time:
- Fall
- Fruit Type:
- Achene
- Fruit Description:
- Ivory colred achene with tufts of hair that fall off as fruits mature.
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Flowers:
- Flower Color:
- Pink
- Purple/Lavender
- Flower Inflorescence:
- Head
- Flower Bloom Time:
- Fall
- Summer
- Flower Shape:
- Urn
- Flower Size:
- < 1 inch
- Flower Description:
- Pink to purple blooms from summer through fall, as they mature they turn a straw color. The 1/2 inch head-inflorecese is urn-shaped.
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Leaves:
- Leaf Color:
- Green
- Leaf Type:
- Simple
- Leaf Arrangement:
- Rosulate
- Leaf Margin:
- Entire
- Lobed
- Hairs Present:
- Yes
- Leaf Length:
- 3-6 inches
- Leaf Description:
- Basal rosette of leaves 2 to 4 inches, lobed or unlobed. Stem leaves are oblong, pinnately lobed to entire and up to 6 inches long. They get smaller and less lobed toward the top of the stem.
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Stem:
- Stem Color:
- Green
- Stem Is Aromatic:
- No
- Stem Surface:
- Hairy (pubescent)
- Stem Description:
- Stems have long, tangled hairs but become smooth and green with age.
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Landscape:
- Problems:
- Problem for Horses
