Tree of the week: Vachellia karoo – Sweet thorn – Soetdoring – Umunga

As we get ready for spring tree planting we would like to remind each other that the Arbor month [September] is around the corner and our Tree of the Year is the Sweet thorn (Vachellia karoo).

Vachellia karoo is one of the most beautiful and versatile indigenous trees of South Africa. It has a life span of 30-40 years and is an adaptable pioneer, able to establish itself without shade, shelter or protection from veld fires. This tree got its common name ‘Sweet thorn’ from the gum secreted from the wounds of the bark.

It has a round crown and starts branching from the bottom. This tree reaches a mature height of about 12m when it gets enough water, it is a fast grower with a growth rate of up to 1m per year. The bark of the Sweet thorn is rough and fissured on older branches and stems. Young branches are reddish brown. It flowers from October to February, the flowers attract masses of insects which in turn invites a wide variety of insect eating birds. This tree is a must for the bird garden.

V.karoo is adapted to various climatic and moisture regimes, it is frost and drought resistant. It can grow well in any soil type. Because of the palatable leaves, flowers and pods, this tree is ideal for fodder. It does not cause hydrocyanic acid poisoning in animals.  Although it makes a beautiful shade tree in the garden, its invasive nature makes it unsuitable for planting near paved areas or buildings.