Acacia sieberiana

Common Name: paperbark thorn

Family Name: Fabaceae

Botanical Name: Acacia sieberiana

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Variety:

Forma:

Cultivar:

Characteristics:

Vachellia sieberiana is a medium to tall deciduous tree growing from 3–25 meters (10–82 ft) tall with a trunk diameter of 0.6–1.8 meters (2–6 ft) and a roughly rounded crown (1, 3). The bark is rough and yellowish, peeling off in rectangular grey-brown scales. A yellow slash with dark red edges is exposed when cut, and the trunk exudes a clear gum (1). The tree is armed with paired, straight white spines at the nodes, measuring 0.6–12 cm (0.24 - 5 in) in length (1). Leaves are bipinnate, sparsely hairy, and arranged in clusters with up to 35 pairs of pinnae and 52 pairs of oblong leaflets (1). Flowers are small (13 mm (0.5 in) wide), cream to pale yellow, and occur in heads on stalks up to 5 cm (2 in) long, either solitary or in clusters (1). Fruits are shiny brown, flat, and indehiscent pods measuring 9–21 cm (3.5 - 8 in) long and 1.7–3.5 cm (0.67 - 1.4 in) wide, each containing around 12 large, hard seeds embedded in yellow-greenish pulp (1). The wood is moderately hard, termite resistant, and off-white in color, used for furniture, tool handles, and mortars (1, 3). The species is nitrogen-fixing and provides shade, forage, and bee forage, especially during dry seasons (2, 3).

Compound: Aca sie

Geographic Origin: Africa

Ecozone Origin: Afrotropic

Biome Origin:

Natural History:

Native to a broad range across sub-Saharan Africa including South Africa, Botswana, Zimbabwe, Namibia, Swaziland, Ethiopia, Kenya, Sudan, and others, Vachellia sieberiana is common in savannahs, riverbanks, and lowlands (1, 3). It replaces Acacia nilotica in southern parts of its range and is particularly well adapted to semi-arid climates. The tree is drought and frost resistant and not considered threatened (1, 3). It is widely browsed by livestock and game, including elephants and giraffes, which helps disperse its seeds (3).

The specific epithet is named after Franz Sieber (1789-1844).

Cultivation Notes: Vachellia sieberiana responds well to coppicing, pollarding, and lopping rebounding with production of many adventitious shoots afterward (1, 4). Seedlings require protection from fire and browsing. Seeds can be stored with added ash to prevent insect damage and are often soaked in water for improved germination, with rates of up to 60% (1). Trees grow quickly and are easily propagated from seed. They are suited for nitrogen-deficient soils due to their ability to fix atmospheric nitrogen (1, 2, 3). It grows well in areas where annual average precipitation is between 400 and 800 mm (15-30 in) (4).

Ethnobotany:

The species has significant cultural and medicinal value. The bark is used to treat fever in children, urinary inflammation, and gastrointestinal issues such as diarrhea and stomach aches (1, 2, 3). Roots, bark, leaves, and gum are employed in treating gonorrhoea, bilharzia, syphilis, colds, coughs, rheumatism, haemorrhage, kidney problems, ophthalmia, and tapeworm (1, 2, 3). The pods are emollient, and a decoction of the root is also used for urethral issues, dropsy, and acne (3). The tree is often used for placing bee hives as its flowers are good as bee forage (4). The bark provides fiber for cordage and bead stringing, while the gum is edible and serves as an adhesive and ink ingredient (2, 3). Other uses of this tree include use for shade, fencing, and windbreaks (1, 2, 3). Leaves contain prussic acid, particularly when wilted, and can be lethal to cattle (1, 3, 4).

Height: 20 - 50 feet

Width: 20 - 50 feet

Growth Rate: Fast Growing

Grow Season: Spring

Flower Season: ForeSummer

Color: Cream

Function: Shade

Spread: Non-spreading

Allergen: Non-allergenic

Invasive: Benign

Toxicity: Toxic

Hardy: Semi-hardy

Water Use: Moderate Water Use

Citations:

Agroforestree Database, Retrieved April 1, 2025
The Green Institute, Retrieved April 2, 2025
iNaturalist, Retrieved April 4, 2025
Useful Tropical Plants, Retrieved May 12, 2025

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