Campulodinium macrocephalum.png 

Natural distribution

Pompom weed has a wide natural distribution that extends from Argentina in South America to Costa Rica and Honduras in Central America and Mexico.

Distribution in South Africa

How or when the plant was introduced into South Africa remains unknown. Currently it is most prominent in Gauteng, but also occurs in Mpumalanga, Limpopo, North West, KwaZulu-Natal, Eastern Cape and Free State. (distribution map) A small patch of plants in the Outeniqua mountains near George have been eradicated but the site will be monitored for regrowth.

 

​The earliest record in the Pretoria National Herbarium is of a specimen collected in Johannesburg in 1962. The earliest record of its establishment in the wild is from Fountains Valley, Pretoria in the early 1960s and Westville near Durban in 1972. In the 1980s its distribution expanded in the Pretoria area, and it was also recorded from Hilton in KwaZulu-Natal and Wolkberg in Limpopo Province. In the 1990s it spread further to Port St Johns in the Eastern Cape, Rooiberg in Limpopo and Nelspruit in Mpumalanga.

Pompom infestation near Fountains, Pretoria, during the 1980s
 

From 2000 to 2003 it exploded in Gauteng and was recorded for the first time in the Free State at Kroonstad. During the same period there was much spread in the Nelspruit, White River and Barberton areas.

By 2006 it had spread to the Piet Retief area in south-eastern Mpumalanga and Swaziland. Surveys in December 2006 recorded many new sites in the Waterberg in Limpopo Province. More surveys in January and February 2007 revealed new records for Polokwane, Haenertsburg, Woodbush, Duiwelskloof, Tzaneen and the Wolkberg in Limpopo, Graskop in Mpumalanga, and the N1 between Vanderbijlpark and Kroonstad in the Free State.

Pompom weed is present along all the major routes around Tzaneen. The most extensive invasion in the Tzaneen area is in the Lekgalameetse Nature Reserve in the Wolkberg, to the south east of Tzaneen. Pompom weed forms extensive stands on ‘The Downs’, a grassy plateau at the top of the Orrie Baragwanath Pass—an area previously inhabited and under potato cultivation. Pompom weed has been present in Lekgalameetse since at least the mid 1980s, with a dramatic increase in abundance since 1997, similar to the sudden and rapid explosion seen in the Pretoria area of Gauteng since the early 2000s. This large infestation of pompom weed at ‘The Downs’ is a huge seed source for invasion of the pristine higher altitude grasslands of the Wolkberg. Already in 2004 pompom weed, which is wind-dispersed, was reported by a hiker in the remote Trichardt’s Pass area of this reserve.

Pompom weed has been recorded at only three sites in the Free State, along the N1 between Vanderbijlpark and Kroonstad and south of Kroonstad on the road to Odendaalsrus. The latter site, at the turnoff to Bothaville, has been known since 2001 when only a few plants were seen. A report was received recently that this infestation has now been cleared chemically by the Working for Water Programme.

Any new sightings of pompom weed can be sent to Lesley Henderson at Henderson@sanbi.org. Please include date, GPS or approximate locality, habitat and abundance. Localities can also be entered at the ‘Weeds and Invasive Plants’ website at www.agis.agric.za/wip.