Know your alien invasive plants

HILLCREST Conservancy will be compiling a series of articles about alien invasive plants to help the community to identify and eradicate them from the gardens.

Sisal (Agave sisalana) is a succulent shrub with thick, sword-shaped leaves in a basal rosette and grows up to two metres high. The leaves are bright green with tiny toothed to smooth margins and the flowers are greenish yellow and are borne on a five to six-metre tall flowering spike. The plant flowers from December through to March, with the leaves poisonous to animals and livestock.

The plant originates in Mexico. It grows throughout South Africa and is very invasive wherever it grows, being listed as a category two plant in the Government Gazette of 1 August, 2014. This means that a permit is required to grow this plant where it is permitted to be cultivated under controlled conditions.

The plant is commonly used as a security barrier plant as it becomes impenetrable once it takes hold. It is, however, very difficult to eradicate and remove, especially when grown on steep banks and in other inaccessible spaces, with this being a costly exercise.

The cultivating of this plant on verges is common in some areas of Highway, where damage was caused to recently-surfaced roads in one case. One wonders whether the property owner will foot the bill for the repairs to this. There are numerous indigenous barrier plants available as an alternative, many of which enhance a property value in addition to being environmentally friendly.

The National Environmental Management Biodiversity Act (NEMBA) of 2014 regulates the growing of invasive plants and will affect all property owners in the future in some way. A large prime property on Table Mountain was recently handed over to the city as it proved too costly to remove the invasive plants.

Contact George Victor on 073 901 3902 or e-mail georgevic@telkomsa.net.