Acacia galpinii

Accession Count: 0
Common Name: Monkey Thorn
Family Name: Fabaceae
Botanical Name: Acacia galpinii
Botanical Synonyms: Senegalia galpinii
Sub Species:

Acacia galpinii is a fast-growing, medium to large tree reaching to 100 feet or more in height, with a symmetrical, rounded canopy (1, 2, 3, 4, 5, 6). It is one of the largest of the acacias (3, 4, 7, 8). The trunk may reach more than six feet in diameter and is covered with rough, yellowish-brown bark that frequently exhibits longitudinal fissuring and persistent thorns (1, 2, 3, 4). The heartwood is dark, often reddish-brown, while sapwood is creamy in color (1, 2). Its wood is hard, dense and coarse grained (1). The tree’s root system is aggressive and may damage buildings and pavement (1, 5, 9). Pairs of dark, recurved thorns, measuring up to ½” long, are arranged oppositely below the nodes on branches (1, 3, 4, 7), and lenticels may be visible on younger branches (1). Leaves are alternate and bipinnate with 6-14 pairs of pinnae, each with 13-40 pairs of leaflets (1, 2, 3). The tree provides dappled shade in the summer, allowing grasses to grow below, and is deciduous in winter (1, 2, 5). Its fragrant flowers, appearing on axillary spikes measuring up to 4 ½” in length, are bisexual and light-yellow to creamy in color with a reddish calyx (2, 3, 6). Flowers give way to brown or reddish pods that can be nearly a foot long (2, 6). Pods, which take about six months to ripen, can dehisce on both sides, releasing the flat, oval seeds (1, 2, 3).

Compound: Aca gal
Geographic Origin: Southern Africa
Ecozone Origin: Afrotropic
Biome Origin:
Natural History:

Acacia galpinii is native to southern and eastern Africa and is typically found in areas of open woodland and thornscrub as well as along riverbanks or in association with termite mounds (1, 2, 3, 4, 5). It is drought tolerant yet thrives in areas of summer rain (1, 2, 9). In its native environment, it grows between elevations of 1100 and 5000 feet (1, 3, 4, 6). It acts as a pioneer species and may be used in afforestation projects (2, 3). It is sometimes used as an indicator plant of well-watered, healthy grasslands (5, 9). As is common with other legume species, the tree readily forms symbiotic root nodules with Rhizobium and Bradyrhizobium bacteria (1, 2, 9). Monkeys often use the species as a refuge and food source, hence its common English name, and other animals, including elephants and giraffes, feed on the tree (1, 3, 5). The tree is fairly long lived (2). The tree’s genus name derives from the Greek word for “thorn” and the specific epithet was named after E.E. Galpin, a naturalist and plant collector from South Africa (2, 5, 9).

Cultivation Notes: This species is most commonly found in loamy or clayey soils (2, 3). Seeds are easy to germinate, but for best germination rates, they should be scarified with boiling water prior to planting (1, 2, 5). The plant prefers a sunny location (3, 5, 9). Once established, the tree is somewhat frost tolerant, but hard frosts may cause some dieback (2, 9). The tree coppices well, particularly when young (1, 2, 9).
Ethnobotany: The wood from Acacia galpinii, which is not typically found in international trade, is hard to work, but yields good furniture (1, 2). It is used as mining timber and to make railroad ties, fences, wagons, flooring, ships and other objects (1, 2, 3). The bark is cut commonly into strips and used to make winnowing plates (1). 
In southern Africa, A. galpinii is grown as a timber crop (9). It is sometimes cultivated as an ornamental plant or is planted along roadsides, and serves as a good shade tree (2, 5, 7, 8, 9), while the thorns also lend use as a security hedge (8). It is sometimes bonsaied or used as a container plant (7), and is considered a good honey tree (1).

Height: 50 - 100 feet
Width: 20 - 50 feet
Growth Rate: Fast Growing
Grow Season: ForeSummer
Flower Season: Fall
Color: Cream
Function: Shade
Spread: Spreading
Allergen: Allergenic
Invasive: Benign
Toxicity: Benign
Hardy: Hardy
Water Use: Low water Use

1. Tree SA. Retrieved April 20, 2020.
2. Plant Resources of Tropical Africa. Retrieved April 20, 2020.
3. Feedipedia. Retrieved April 20, 2020.
4. JSTOR: Global Plants. Retrieved April 20, 2020.
5. South African National Biodiversity Institute. Retrieved April 20, 2020.
6. Flora of Botswana. Retrieved April 20, 2020.
7. PlantInfo. Retrieved April 20, 2020.
8. Random Harvest, ( Retrieved April 20, 2020.
9. Useful Tropical Plants. Accessed April 20, 2020.

Acacia galpinii