Phytolacca dioica On a lighter note we look at some less awful but still threatening invasives by way of change. Our subjects for this instalment are two species of Phytolacca commonly found in our area – many of us will be particularly familiar with P. octandra (Inkberry) which is a very common herbaceous weed along Whites and Waterside Roads. P. dioica (Belhambra tree) on the other hand was punted in the fifties as particularly desirable for its handsome shape and was recommended for groves, shade and shelter for stock on farms. It has all those exceptionally desirable qualities – (the same ones that cause them to become invasive) quick-growing, OK with poor soil and drought, except – it could not cope with severe frost – therefore perfect for this region. The other species P. octandra is reported to have come into KZN during 1865 when work was in progress on the railway cuttings between Durban and Pietermaritzburg and has since worked its way down along the coast right into the Western Cape. Both species have their origins in South America.
Perhaps lesser-known is that both species are poisonous and P. octandra can cause skin irritation. Instances of stock deaths have been recorded and the toxins are potentially lethal to humans. The leaves, roots and fruit are thought to be toxic.
Identification: The Belhambra tree or bobbejaandruifboom is a large evergreen or semi-evergreen tree up to 20 metres tall with a spread of around 12.5 metres. A feature of this soft-wood tree is its short buttressed trunk. The leaves are large, ovate and bright green born on slightly pinkish stalks - both leaves and stems are succulent. The herbaceous Inkberry/Inkbessie in turn very quickly grows into a substantial shrub. It is easily recognised by its large strong green leaves. The flowers of both species are insignificant, pale cream racemes. The fruits of both species are characterised by the plump fleshy green berries that turn black as they ripen. Crushing the fruit produces a juice that makes dark blue/red stains on hands and clothes that are very difficult to clean.
Invasive Status:Phytolacca dioica is a declared invader (Category 3 – no trade permitted). The seed of both species is attractive to both birds and baboons and as a consequence seed dispersal is very effective. Seeds germinate readily. The Belhambra tree invades savanna, fynbos, coastal bush, riverbanks and roadsides. P.octandra is on the X List as a proposed Category 1. These plants are major weeds in the forestry industry where clear-felled areas are rapidly invaded. In our area they appear in large numbers in road verges and on disturbed sites.
Control: Thankfully both are easy to control – hand-pulling of seedlings is easy and effective. P.octandra is also susceptible to herbicide application. Luckily P.octandra is not a subject that keen gardeners would plant in their gardens willingly – it usually just appears (effective seed dispersal by birds). Just keep an eye and pull out before it reaches the fruit stage.
Indigenous substitutes: Karee (Rhus lancea) is a moderately fast-growing tree with a very pleasing shape. The Tasselberry (Antidesma venosum) has a non-invasive root system as has Vepris Lanceolata (White Ironwood). All these will thrive in our area and are great choices for attracting birds.