Pink knotweed is a low, creeping perennial from the Himalayas and southern China, grown as a groundcover for its round pink flower heads and leaves marked with a dark V. It isn't native to the U.S. and has escaped gardens to grow wild in California and Hawaii. It's also called Himalayan smartweed.
Appearance
- Growth form
- A mat-forming perennial whose stems root wherever they touch the ground.
- Leaves
- Small leaves, about 0.4–2.4 in (1–6 cm) long, with a dark reddish V-shaped band and short scattered hairs.
- Flowers
- Tiny pink flowers packed into round heads about 1/4 in (5–7 mm) across.
Where it lives
- Typical habitats
- gardens
- lawns
- roadsides
- disturbed ground
- Range
- Native from the Himalayas to southern China and Indochina. In the U.S. it has in California and Hawaii.
- Preferred conditions
- Tolerates shade and many soil types, and does well in moist, disturbed spots.
Life cycle
- Reproduction
- Spreads by seed and by rooting stems. Seeds travel in water, soil, and garden waste and with birds, and plants can mature within a single growing season.
Growing it
- Care
- Sold as an ornamental groundcover.
Conservation
- IUCN Red List
- NENot EvaluatedNot yet assessed
- Status
- Hawaii's weed risk assessment rates it high risk for becoming invasive.
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