Invasive Cape Town Plants

Cape Town is under threat from numerous invasive terrestrial and aquatic plants. These invaders threat the unique biodiversity of the region and also threaten water quality.

Invasive Terrestrial Plants

According to the City’s Invasive Plant Database, the most widely invasive alien plants in the Cape Town metropole - as measured by area - are:

  • Port Jackson willow (Acacia saligna)
  • Longleaf wattle (Acacia longifolia)
  • Rooikrans (Acacia cyclops)
  • Australian myrtle (Leptospermum laevigatum)
  • Stinkbean (Paraserianthes lophantha)
  • Grey poplar (Populus x canescens)

The most abundant species in mountain catchments are:

  • Pines (Pinus radiata, P. pinaster)
  • Hakea (Hakea drupacea; H. gibbosa; H. sericia)
  • Black wattle (Acacia mearnsii) in riparian zones

Other problematic species include:

  • Giant reed (Arundo donax)
  • Kikuyu (Pennisetum clandestinum)
  • Morning glory (Ipomoea purpurea)
  • Manatoka (Myoporum tenuifolium)
  • Canna (Canna indica)
  • Lantana (Lantana camara)

Various invasive grasses and herbaceous and annual weeds invade road verges, disturbed areas and even nature reserves, e.g. Fountain grass (Pennisetum setaceum), Blue Echium and Patterson’s curse (Echium vulgare, E. plantagineum), as well as Tree mallow (Lavetera arborea).

Invasive Aquatic Plants

  • Water hyacinth (Eichhornia crassipes)
  • Water lettuce (Pistia stratiotes)
  • Kariba weed (Salvinia molesta)
  • Parrot’s feather (Myriophyllum aquaticum)
  • Red water fern (Azolla filiculoides)
  • Rigid hornwort (Ceratophyllum demersum)
  • Brazilian waterweed (Egeria densa)
  • Purple loosestrife (Lythrum salicaria, L. Lythraceae)
  • Watercress (Nasturtium officinale)
  • Persicaria (Persicaria lapatihifolia)
  • Pickerel weed (Pontederia cordata)
  • Yellow water lily (Nymphaea mexicana)