Download Article 54 Phytolacca dioica Belhambra and octandra Inkberry

Weeds in our Area (Part Fifty Four)
By Bob and Ena McIntyre – Garden Route Branch.
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.
References: “ALIEN WEEDS AND INVASIVE PLANTS” : Lesley Henderson. Copyright © 2001
Agricultural Research Council. Problem plants of South Africa: Clive Bromilow, Poisonous Plants of
South Africa: Ben-Erik van Wyk et al. Ornamental Shrubs and Trees for gardens in Southern Africa:
Una van der Spuy