Queensland umbrella tree
The Queensland umbrella tree is a tall, evergreen tree which can be single or multi-stemmed. It is also epiphytic, growing on other trees. The aerial roots eventually smother the host tree. This is a tropical species and therefore mostly confined to coastal KwaZulu-Natal.
Grown as an ornamental, it is increasingly infiltrating natural coastal forest to the detriment of indigenous vegetation. The glossy green leaves form an umbrella-shaped pattern.
A medium-sized annual herb which was grown as an ornamental. It is invasive in many nature reserves where it thrives under shaded areas and along streams. The impacts are not known but large invasions are may potentially transform the habitat.
Wild tobacco is widely distributed across South Africa and invades fynbos, karoo, grassland and savanna. It is highly adaptable and a potential habitat transformer and bush encroacher. All parts of the plant are known to be poisonous to livestock and game. It also invades roadsides, disturbed or cultivated land, riverbeds and natural vegetation.
Four o’ clock
An erect, bushy herb which flourishes during the summer rainfall season. It thrives under trees and other shaded areas, as well as along streams. It can form dense thickets. The common name four-o-clock alludes to the opening of the flowers in the late afternoon. During bright sunny or hot weather, the flowers shrivel up, but on overcast or rainy days they are showy and prominent. Flowers are red, pink, yellow or white. It is common throughout urban Johannesburg.
The syringa, together with lantana, are perhaps the two best known invasive plants in South Africa. Syringa were extensively planted as municipal pavement trees but have subsequently become one of the most widespread and notorious invaders across the county.
A deciduous spreading tree which produces bright lilac purple flowers in spring with persistent yellow berries remaining on the tree in winter after the leaves fall. The ripe fruits are toxic to humans and animals, but despite this, are still eaten by certain birds. This tree is common along national roads in rural areas. Unfortunately, it is a serious problem inside national parks and nature reserves where it disrupts the natural biodiversity of these natural areas.
The mallow is a small biennial invasive herb growing one metre high. The stems and leaves are soft and hairy. It was cultivated as an ornament but shows invasive tendencies, although largely confined to disturbed sites. It may invade riverbanks and streams.
The Formosa lily hails from Taiwan but has found a new home in South Africa’s high rainfall grasslands. It has become a competitive invader in natural grasslands. It can be mistaken for indigenous lilies which have similar flowers.
The flowers appear in late summer. There appears to be three main populations. A large concentration is found in southern coastal KwaZulu-Natal and the Midlands, with a cluster in the Mpumalanga and Limpopo escarpments. They favour moist and misty grasslands, but will infiltrate plantations and coastal forest.
The bleeding-heart tree is part of the euphorbia family. This plant comes from New Guinea and Australia and was imported as an ornamental. Like most euphorbias, it exudes a poisonous milky latex from the stems and leaves.
It is a hairless shrub or small tree reaching up to 8 metres in height. It has been identified in several parts of the Western Cape where it invades plantations, indigenous forests, streambanks and roadsides.
Yellow ginger lily
The yellow ginger lily is one of several species which have become invasive. They are commonly encountered in and around urban areas as well as inside nature reserves. In KwaZulu-Natal they prefer the slightly cooler climates around Kloof and Pietermaritzburg, where they grow under the protective cover of large trees.
This is a habitat transformer and can form extensive shrubby stands. They have invaded several nature reserves in KwaZulu-Natal and continual efforts are underway by various conservancies to combat this plant.
Moon cactus is another invasive species that thrives in the savanna or bushveld region. Cacti often form dense clusters at the expense of indigenous plants.
Effective biocontrol is available to control the spread of this cactus. It is a spiny succulent shrub with elongated ribbed cladodes and produces a bright orange or red fleshy fruit. It is common in the Tshwane / Pretoria region and throughout the Magaliesberg.