Many alien plants that have become such a nuisance that they have to be actively eradicated in places are pretty. Doubtless it is their attractiveness that encouraged people to import them for their gardens in the first place. Yet, most of our common garden flowers have originated from elsewhere and no-one turns a hair, so what makes an ‘alien’ an ‘alien’ that becomes known as a ‘noxious weed’ or an ‘alien invasive’? When the rate at which they spread, the harm they do to natural vegetation, and the potential risk they hold for animals and humans become a problem.
Common lantana (Lantana camara) is one such pretty alien.
It originated in tropical America and has spread alarmingly all over the world. In South Africa, both the Eastern Cape and Kwa-Zulu Natal are particularly affected by the infestation of these plants which were originally imported as an ornamental garden shrub. There is no denying the beauty of their multi-coloured yellow-orange flowers.
Birds eat the fruits and in this way the plants have moved from gardens to the veld. Therein lies the problem: this plant is one of the most common causes of livestock poisoning in this country and is thus classified as a Category 1b invasive alien species in the South African National Environmental Management Biodiversity Act of 2004. This means that they have to be removed and destroyed as part of an invasive species control programme.
Common lantana spreads and grows so rapidly that it out-competes indigenous plants by forming dense thickets. These reduce natural pasturage – which obviously affects the amount of grazing available, access to water supplies and severely reduces biodiversity.
Henderson Mayda and Anderson Johan G. Common Weeds in South Africa. Department of Agricultural Technical Services 1966.
Van Wyk Ben-Erik, van Heerden Fanie and van Oudtshoorn Bosch. Poisonous Plants of South Africa. Briza Publications 2005.
The five trees featured below are not indigenous to South Africa, although to call them aliens at this stage might be a misnomer as they have settled in and made themselves quite at home. Some are so familiar that we rarely think about them ‘not belonging’ and others make a nuisance of themselves particularly in riparian areas. Even though the fruit of some are poisonous, all were brought into the country at one time or another either because they were attractive or had some perceived use. We are stuck with them so need to be wary of their march through the country, all whilst admiring them for some of their qualities.
Around about three hundred different types of Eucalyptus trees have been introduced to this country – mainly for the forestry industry which supplies timber for anything from mining to furniture, as well as the paper industry. They grow fast and were popular choices for windbreaks and even for some public parks.
The long-leaved wattle (Acacia longifolia) is a highly invasive tree that was originally planted here to assist with the reclamation of sand dunes. It is easy to see why they compete with indigenous species of trees as they tend to grow in stands so thick that they are actually difficult to walk through – and nothing grows underneath them. Their flowers are very attractive though.
Melia azedarach or syringa trees were imported from India for their ornamental properties. They grow into a beautiful shape that provides much-needed shade during our hot summers, have beautifully scented lilac flowers, and even the bunches of golden berries that follow are attractive – although very poisonous!
Another tree cultivated here – especially as street trees – for its ornamental properties is the Brazilian pepper tree (Schinus terebinthifolia) which, as the name suggests, originated in South America. Of course one can never tell what the long-term consequences of planting alien trees might be: decades on, municipalities are having to face the fact that the roots of these trees not only break up the pavements but invade sewers and drains. The attractive berries are toxic too.
Quercus robur is apparently the most common of the oak trees that proliferate in the Western Cape and which have made their way through much of the country – they too have been popular as street trees or for providing shade in public parks. Even though these trees are slow growing, some have strayed from their original sites and managed to grow to a fair size.
The Silver Wattle (Acacia dealbata) is a fast-growing evergreen tree which can reach a height of 5-10m. Their bark is grey-brown to almost black, while their short frond-like leaves with fine hairs often look silvery-grey from a distance.
There is no denying that when they are in bloom, these trees look very attractive. Clusters of rather attractive fluffy yellow flowers are followed by straight, hairless seed pods. These bright yellow blooms appear in this part of the Eastern Cape from about August through to November.
The Silver Wattle originates from South-eastern Australia and Tasmania. Some sources believe it may have been introduced to South Africa in error, having been confused with Black Wattle (Acacia mearnsii) – originally imported for the tanning industry.
There is a thick infestation of these trees not far from where I live and I often see people loading their donkey carts with green saplings to be used for building rondavels or gathering older wood for cooking fires in areas with no electricity.
The Silver Wattle spreads both by seed and root suckers – especially along streams and in moist upland areas.
In some places it grows so close together that these thickets absorb large amounts of water that would otherwise run-off to replenish natural water sources as well as dams. Its spread and rapid growth causes it to replace indigenous grassland – which naturally restricts grazing for livestock – and competes with riverine species of trees.
Whenever I scroll through my photographs I am surprised at the number of patterns that jump out at me. At the risk of boring readers with yet another lot, I have a few more to show. The first are raindrops on the grass. There is a great delight in these shining drops for we received some unexpected rain last week – enough to green up the grass on my unmown lawn and to give the flowers in the garden a ‘lift’:
After the rain comes sunshine and these patterns shining on the side of our swimming pool caught my eye. The pool was filled with grit and leaves after the rain:
Thanks to the ongoing drought, it is a while since I have been able to enjoy large marigolds in the garden. None of the many seeds planted this year have shown a sign of sprouting. Nonetheless, I enjoyed finding this picture in my archives:
I have shown several Eucalyptus trees of late; here is a closer look at the leaves of one of the trees growing around the corner from where I live:
Next is a picture regular readers may be familiar with. This is Bryan, the angulate tortoise that came to live in our garden for some time until eventually the desire to travel on overcame him. I love the pattern on his shell:
Lastly, I cannot resist adding this stained glass window:
We start our view of scenes from my part of the Eastern Cape with a quick trip to Middle Beach at Kenton-on-Sea, which is only about 40 minutes from where we live.
When driving through the Lothians area, where the rest of the photographs were taken, we come across a few avenues of Eucalyptus trees like this one that were probably originally planted to provide a windbreak on the farms.
There are a variety of farms in this area so it is common to come across horses, sheep and cattle. Every now and then though we may see a warthog in the veld.
The road I regularly travel on is a dirt road with no clearly defined verges. Instead the wild grass grows right against the edges.
I always keep an eye out for wild flowers and, at this time of the year, purple Senecio macrocephalus are making a fine show all over the veld.
One cannot help noticing the bright orange spikes of the tall Aloe ferox dotted all about the Eastern Cape veld at this time of the year.