Alien Invasion: Woolly Plectranthus
(Plectranthus barbatus var grandis) South African Invasive Category 1b in terms of the Alien & Invasive Species Regulations (ie illegal to have on your property, propagate, or sell).
A large, soft shrub with large, softly hairy leaves and columns of conspicuous purple flowers.
Woolly Plectranthus What does it look like? Where does it come from?
Possibly from India.
Why is it bad?
This is a “passive aggressive” invader: while not one of the worst of our nasties, it is slowly taking ground in the Eastern Cape.
It can be found naturalised in a wide variety of habitats in and around Grahamstown, from urban open areas to streamlines, woodland margins and roadsides.
It has become extensively naturalised around Kentonon-sea, Bushmans River, on lo- cal farms, and in parts of the Transkei. The main source of invasion is from being planted extensively as hedging around gardens and kraals, and in gardens.
How can I control it?
This is an easy plant to control. It can be hand-pulled, cut near the base and the stumps treated, or the whole plant sprayed with a suitable herbicide.
It’s main trick however is to re-grow (and spread) from the many broken pieces of plant, so all parts of the plant need to placed in plastic bags and either burnt or disposed of at the main rubbish tip (not at a garden refuse site).
What can I replace it with?
PSouth Africa has a beautiful array of indigenous Plectranthus species. For gardens, Large Spurflower ( pecklonii, with at least three cultivars) is a spectacular alternative straight from our eastern forests.
Those of us who’ve done the Katberg trail runs will be familiar with it. Other shrubby options are Mona Lavender ( Plectranthus ‘Mona Lavender’) and Zululand Spurflower ( P zuluensis), although both of these are frost sensitive.
Misty Plume Bush ( Tetradenia riparia) is a fast-growing shrub similar to the shrubby forest species of Plectranthus, and it can be easily grown from cuttings.
Also consider Pride-of-DeKaap ( Bauhinia galpinii), Karoo Rhigozum ( Rhigozum obovatum), Dwarf Coral Tree ( Erythrina humeana) or September Bush ( Polygala myrtifolia) as brightly colourful replacement shrubs.
For alien invasive species advice, property assessments, alien control plans and practical assistance contact The Alien SWAT Team: Dr Ralph Clark 072 439 8981 andTimothy Mattison 060 527 7816;