Tuesday, February 01, 2005

These Plants Are Sharp!


The acacia (accasia karroo) is the trademark plant for Africa. I guess Asia's equivalent is the Ginko. It can be used for anything from sewing needles to impenetrable kraals, as the Zulus have done to protect their herds of cows from lions.

From: http://www.plantzafrica.com/plantab/acaciakar.htm
The name Acacia is derived from Greek "akis" a point or barb. Karroo is one of the old spellings of karoo which cannot be corrected because of the laws governing botanical nomenclature (giving of names).

The sweet thorn gets its common name from the gum which is exuded from wounds in the bark. This pleasant tasting gum is eaten by people and animals, including the Lesser Bushbaby which feeds exclusively on insects and gum from trees, particularly acacia trees. It also had commercial value in the past when the gum was exported as "Cape Gum" for making confectionary. This is apparently similar to gum arabic which is used as a water soluble glue.

It is a particularly good fodder tree, stock and game feed on the leaves, flowers and pods. Seed dispersal takes place this way. There is no danger of hydrocyanic poisoning which is a self-protection mechanism used by many trees. The bark contains tannin which is used to tan leather to a reddish colour. (This unfortunately gives the leather an unpleasant odour). The heartwood is heavy and hard but susceptible to attack from borer. This apparently may be prevented by seasoning the wood in water for six months before use.

The "Dune Forest" form found along the coast of Kwazulu-Natal northwards of the Tugela river has soft wood so would not be suitable for woodworking. A strong rope can be made from the inner bark which is pliable enough for rope-making when it is wet. The flowers produce lots of nectar and pollen for bee-farming and the honey has a pleasant flavour. In arid areas the sweet thorn is an indicator of water, both underground and surface. It was a very welcome sight to early travelers and nomads.

Acacia karroo has a life span of 30-40 years and is an adaptable pioneer, able to establishing itself without shade, shelter or protection from grass fires. Once over a year old, seedlings can resprout after fire. Several fungi are associated with this tree and the crown of mature trees may be parasitized by various mistletoes, leading to the tree's decline. This tree has a long taproot which enables it to use water and nutrients from deep underground, this and its ability to fix nitrogen, lead to grasses and other plants thriving in its shade.

The sweet thorn has many medicinal uses ranging from wound poultices to eye treatments and cold remedies. The bark, leaves and gum are usually used. It is also used to treat cattle which have tulp poisoning (Homeria spp - bulbous plants which are poisonous to stock).


In some species the leaves close when touched, almost like a living animal, and as far as I know, they shoot up the tannin levels when neighboring plants get consumed, and then by the time the herbivore (buck, or rabbit) gets to the tree, it tastes bitter and the feeders have to trot along somewhere else where the plant signals haven't reached yet. This insures that areas are only partly consumed rather than completely destroyed a la human patterns of consumption.

Nature knows how to moderate to sustain itself. Do we? Posted by Hello

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