Acacia galpinii - CJM Tree Growers

(presently Senegalia galpinii)

General

DESCRIPTION

One of the tallest and largest of the naturally occurring Acacias, the Monkey Thorn is a robust, fine tree, with beautifully flaking bark, a wide, somewhat spreading or domed canopy of luxurious, pale green, feathery foliage, large, dark, arched thorns and masses of striking, creamy, bottlebrush-like flowers, that are an unusual purple-red before they open. The dainty leaflets fold up at night. The common name is believed to refer to tendency of monkeys to take refuge in amongst the thorny branches and their love of eating the pods. It is often mistaken for Acacia (Senegalia) polyacantha, but the latter lacks the gland dot on the leafstalk.

SA TREE

FAMILY

Fabaceae or Leguminosae (Legume or pod-bearing family).
This family is also divided into 3 subfamilies; mimosa or acacia subfamily, cassia and pea. Regarded as one of the largest, as well as economically significant families, its members have been cultivated since early times for their plethora of uses – as food, medicine, fodder, for practical use (tannins) and ornamental displays.

HABITAT

From Tanzania in the north, also Zambia, Malawi, Zimbabwe, to the northwest province in southern Africa, Gauteng and Mpumalanga, where they are naturally and predominantly found near water. They frequent bushveld and open or wooded grasslands, up to altitudes of 1500m. They are believed to be indicators of sweet veldt.

Main Features

BARK

Pale, yellowish-grey and flaking in long, papery strips when young. As the tree matures, the bark becomes darker brown and rougher, with deep longitudinal grooves and a corky or papery texture. New twigs are a light, creamy yellow, glabrous or slightly hairy and faintly corky. The main stem is typically straight, with a diameter of 600-1500 mm.

FOLIAGE

Deciduous.
Bipinnately compound leaves (50-110 mm), with 8-14 pairs of pinnae, each with 12-40 pairs of fine, oblong, hairless leaflets (35-110 x 10-20 mm). A smallish gland dot can often be seen on the petiole (10-40 mm), but its position is variable. The thorns are stout, strong, dark brown and more or less straight or hooked, and grow in pairs just below the nodes or on the branchlets, rarely on the main trunk.

FLOWERS

Elongated, slender, honey-scented, buttery yellow spikes, produced en masse. Juvenile buds are reddish to purple (unique among the Acacias) and are usually produced before the new leaves. (September-October)

FRUIT

Pods, reddish to purplish, (25-28 x 2.5-3.5 cm), with a slightly brittle texture. They are smooth, slightly thickened, and split on the tree. (February- March)

HEIGHT

SPREAD

Uses

MEDICINAL

The bark has astringent properties, and decoctions, infusions or powders are used internally and topically. It is used internally to bring relief from stomach complaints, dysentery and diarrhoea, as well as cases of internal bleeding. A cleansing body and mouth wash is also made from the bark, and this is used to treat wounds, rashes and other skin ailments, haemorrhoids, excessive perspiration and certain eye infections.

PRACTICAL

The creamy-yellow sapwood can clearly be distinguished from the dark reddish bronze heartwood. The wood is hard, heavy, irregularly grained with a slightly coarse texture. It is very tough and durable, takes a good finish, but is difficult to work. Quality furniture has been made from it, as well as poles for fences, wagon parts, implements and implement handles, railway sleepers and flooring panels. The timber is also used for shipbuilding and in joinery and is relatively resistant to attack from parasites. Due to the presence of tannins in the bark, it is often used to add colour to leather. A quality, strong rope can be made from the fibrous inner bark.

WARNINGS

The leaves of most Acacias contain traces of the toxin Hydrogen cyanide, which can be fatal if ingested. The concentrations of the chemical increase during periods of drought or over-grazing. The trees also have an aggressively spreading root system, so should be planted clear of any permanent structures or pools.

Landscape

WILDLIFE

The flowers attract a host of insect life – wasps, beetles, honeybees and butterflies, but may also lure certain insectivorous bird species that prey on the insects. The gum is eaten by monkeys, baboons and many insects. Although the pods are a favourite of certain monkeys, they are eaten less frequently than other Acacia pods. The leaves are occasionally grazed by game and stock animals, and the trees provide valuable shade for many farm animals. Birds love to build their nests high up amongst the concealing, thorny branches, and monkeys are also known to take shelter in the trees.

ADVANTAGES

The trees adapt well to cultivation, and provide lovely, dappled or deep shade. Although they may grow too large for the average garden, they are perfectly suited for reserves, farms, parks, large gardens and street planting. The trees are a spectacular sight when they are in full bloom and make fine specimen trees. They respond well to pruning, and, if planted in groups and regularly trimmed, they will make excellent security or screening hedges. They are quite long-lived trees, and, unlike many other Acacia species, they do not have a habit of throwing their thorns.

Cultivation

TOLERANCE

Once the trees are properly established (3-5 years), they are able to withstand considerable amounts of frosts, but young trees should be sheltered as extremely cold conditions could severely damage them. The Monkey Thorn can endure extended periods of drought once mature, but should be given regular, deep drenching’s when young. They are wind hardy.

GROWTH RATE

LIGHTING

SOIL & WATER

The trees accept a wide variety of soil conditions, from sandy, clay to loamy, with a neutral ph, but prefer well-drained soils. They will respond well to added compost, and have moderate water needs, only requiring extra watering during very hot and dry periods. The Monkey Thorn thrives naturally in dry, frost-free summer rainfall regions.

PROPAGATION

Prior to being sown, the hard seed coat needs to be broken or softened to speed up the germination process. This can be done by soaking the seeds for 12-24 hours in very hot, but not boiling, water. If they are not swollen by the next day, a small nick can be made in the seed coat (be careful not to damage the embryo!) and the process can be repeated. Thereafter, the swollen seeds can be sown in a well-drained mixture of compost and river sand (1:2), and then covered with another thin layer of sand. Place in a warm, bright area and mist often. Germination is usually rapid, within 1-3 weeks. Seedlings can be transplanted into individual containers once they reach the two-leaf stage. Saplings can be planted out into open ground after one or two years and should be watered regularly until well established.