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GRAANGIDS
2016
GRAIN GUIDE
Ten main invasive plants in South Africa
Continued from p. 82
Continued on p. 86
Campuloclinium macrocephalum (Less.) DC.
The pompom weed is indigenous to South and Central
America and Mexico, where it was used as an ornamental
plant. It is an erect, perennial herb that becomes up to
1,3 m tall. The plant has a short, woody rootstock ending in
thick tuber-like or bulb-like roots. The pompom weed focuses
exclusively on survival. Its extremely well-developed subterra-
nean structures (rootstocks and tubers/bulbs) make it possible
for the plant to survive difficult times. The stems and leaves
constitute only 30% of the total biomass of the plant, which
implies that the underground structures constitute about 70%.
It can survive fire, cold and frost, as all the living parts of the
plant are dormant below ground in these periods. During
droughts in summer the plants can also become dormant be-
cause they withdraw the nutrients from the stems and leaves
and store them in the underground roots. The plant has
therefore developed survival strategies that enable it to increase rapidly in grassland and savan-
nah areas. The pompom weed occurs in a great variety of habitats and in various types of soil. It
usually occurs in very disturbed areas like road reserves, as well as in old fields that are no longer
tilled, from where they spread to grasslands. The negative aspects of the pompom weed include
the following: It reduces grazing capacity; it has possible allelopathic properties, which implies
that it contains chemical substances that have a negative effect on the growth and development
of other plants; if field hay is made and the plant is present in large quantities, the quality of the
hay is reduced because of the hairy stems and leaves; if it occurs in cultivated fields, the grain
yield can be reduced because of the possible allelopathic properties; it has the ability to produce
an enormous number of very vigorous seeds; it develops rapidly from seed to mature plant in one
season. Mechanical control of this plant is not recommended at all, as it only causes new plants to
develop from the underground storage organs. Biological control agents against this plant have
been released and various others are being investigated. The success of the released bio-agents is
not yet known. Various chemicals are registered for controlling the plant. According to the CARA
Act the pompom weed is a category 1 plant – the landowner must therefore control it.
Cortaderia jubata (Lem.) Stapf
Pampas grass originally came from South America (Ecua-
dor, Peru to Argentina) and was brought to South Africa as
an ornamental plant. It is a robust, large tussock grass that
can be up to 3 m in diameter and up to 3 m tall. Pampas
grass establishes particularly easily in moist sandy soils, but
the grass has adapted to the extent that it occurs in virtually
any soil and in any habitat. It occurs particularly in disturbed
areas like road reserves, but also invades grasslands, rivers
and coastal dunes. It has a deep and well-developed root
system and grows very quickly. Propagation occurs through
seeds – allegedly a single inflorescence can form 100 000
seeds. These seeds are light and are easily dispersed by the
wind. They are also dispersed by water, animals, vehicles
and humans. The negative aspects of pampas grass include:
Smothers indigenous vegetation by overshadowing the
plants; competes with other plants for light, space, water and
nutrients; it is drought resistant and therefore survives stressful
conditions; changes the landscape and habitat; increases
Campuloglinium macrocephalum
Cortaderia jubata