Gorgeous Green House

The Renovation Journey of a 1940’s ‘Traditional’ to 2015 ‘Contemporary, Green & Gorgeous’

Pretty but Dangerous: alien plants do harm


Image result for Senna bicapsularisPretty yellow flowering shrubs are currently blooming all over Durban (and further afield).  What many people don’t realise is that these plants are alien invaders.

A plant is classified as ‘alien’ when it has the ability to spread without the assistance of people and is destructive to the environment, bio-diversity or human interests.

They are fast growers, produce massive amounts of seed and because the come from countries with different ecosystems the usual predators, diseases and parasites that keep them in check are not in place.  They overtake our indigenous plants and upset the equilibrium that eco-systems require to be healthy.  As plant species are crowed out the insect, bird and animal species are likewise impacted.

Distinctive leaf and flower makes identification of this alien easy

I was quite shocked to discover at the Gorgeous Green House  that I had three of these pretty ‘horrors’ lurking behind my Carissa hedge. Alerted only because they’ve just come into flower.  Time now being of the essence (before they set seed and pollute my entire neighbourhood) we needed to get out the clippers. It didn’t take long to get them down to stumps as the wood is fairly soft.  It is  imperative after this step to  ‘kill’ the stump with a mixture of diesel and herbicide (your nursery will advise).  No need to break your back digging the things out.  Keep an eye on it though as they are tenacious and may need follow-up ‘painting’ as they will try to sprout.

Now the fun part begins!  What to replace them with?

Flowers of Ochna serrulata

Carnival Ochna, Ochna serrulata

Tree Laburnum, Calpurnia aurea

Curry Bush, Hypericum revolutum

Yellow bauhinia, Bauhinia tomentosa

There are so many gorgeous indigenous (native) yellow flowering trees and shrubs that we are spoilt for choice.  Indigenous alternatives will draw birds, butterflies and other wildlife while still providing the beauty the Senna offers.  If I consider alternatives that have similar visual appeal these top my list:  Showy Ochna (Ochna natalitia), Carnival Ochna (Ochna serrulata),  in fact the whole Ochna family, some are better inland, Curry Bush (Hypericum revolutum) though that’s also better slightly inland not coastal, Wild Laburnum (Calpurnia aurea), Senna petersiana would be great for the highveld, and Yellow Bauhinia (Bauhinia tomentosa).

Senna pietersiana

If you don’t live in my province or country these options obviously don’t apply.  A good nurseryman will know local indigenous plants for you.

Failing which of course there is always the power of Google!

I’m going to print this page and pop it into the post boxes of neighbours who have these plants, I hope they find it helpful.


2 thoughts on “Pretty but Dangerous: alien plants do harm

  1. Love your blog. Quick question. Surely the diesel and pesticides are toxic to the environment?

    • Excellent question Dee. Firstly, you must use a herbicide not pesticide which is not terribly toxic, neither is diesel in small quantities. However, your point about toxicity is totally relevant because it can be harmful to plants in the vicinity. I make my mixture and then literally paint only the raw edge of the offending plant. In this way only that plant is affected.

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