Knotweed

Persicaria capitata

Common name:

Knotweed

Scientific name:

Persicaria capitata

Alternative common names:

Japanese knotweed, persicaria, pinkhead knotweed and pinkhead smartweed.

Knotweed is a mat-like, perennial, herbaceous plant with a slender, woody rootstock and long, creeping, rooting stems. It is found growing on roadsides, dry banks, slopes and in open areas, preferring full sun. It negatively impacts on the environment by forming a dense carpet, replacing most indigenous vegetation. 

Additional Info

  • Where does this species come from?

    Asia.

    What is its invasive status in South Africa?

    NEMBA Category 1b.

    Where in South Africa is it a problem?

    Limpopo.

    How does it spread?

    Seed and vegetative dispersal.

    Why is it a problem?

    It competes with and has the potential to replace indigenous species.

    What does it look like?

    Leaves: The hairy leaves are 1-6cm long and 0.7-3cm wide with a reddish midrib giving a distinctive red ‘V’ pattern. The leaves turn red when the plant is under stress. Flowers: The tiny pink flowers are clustered in ball-shaped flower spikes above the foliage. The ball-like inflorescences are 7-20mm across with numerous pink flowers 2.5mm long. Flowering occurs from October to March. Fruit/seeds: Produces a small, brown nut, triangular in cross-section, 5-10mm long.

    Does the plant have any uses?

    Ornamental groundcover.