Acacia tortilis (Forsk.) Hayne
Syn.: Acacia raddiana Savi,
Acacia spirocarpa Hochst. ex A. Rich
Acacia heteracantha Burch.
Umbrella Thorn, Israeli Babool
Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.
- Folk Medicine
- Yields and Economics
- Biotic Factors
Since this is one of the few timber species of the Arabian deserts, it is
suspected as being the wood from which the Biblical Ark of the Tabernacle was
made. Kaplan (1979) says rather emphatically it is the Shittim of the Bible,
which provided the Israelites with the large-size timbers for the Ark. The
timber is also used for fenceposts, firewood, furniture, and wagonwheels. The
prolific pods made good fodder for desert grazers and the foliage is also
palatable, being one of the major dry season fodder trees for the
Sahara-Sahelian belt. Bark, used for string in Tanganyika. Gum used as a poor
man's gum arabic, said to be edible. It is the tree most recommended for
reclaiming dunes in India and Africa (Roy et al, 1973). The thorny branches
are used to erect temporary cages and pens. Bark said to be a good source of
tannin (Roy et al, 1973). Africans once strung the pods into necklaces.
Senegalese use the roots for spear shafts, Lake Chad natives use the stems for
fish spears. African nomads often use the flexible roots for frameworks of
their temporary shelters.
While I find few data specific to this species, I suspect that the gum is used
like that of gum arabics in folk remedies. In French Guinea, the bark is used
as a vermifuge and dusted onto skin ailments (Dalziel, 1937).
Pods contain close to 19% protein (Palmer and Pitman, 1972). NAS (1979)
reports unconfirmed allegations that the foliage can be toxic to livestock.
Certainly HCN has been reported in several Acacias. The following tables are
reproduced, with permission, from FAO's Tropical Feeds (1981):
Nutritive tables (Gohl, 1981)
Acacia tortilis (Forsk.) Hayne subsp. heteracantha (Burch.)
| ||As % of dry matter|
| ||DM ||CP ||CF ||Ash ||EE ||NFE ||Ca ||P ||Ref.|
|Fresh leaves, South Africa || ||19.2 ||11.6 || 8.7 ||6.1 ||54.4 ||2.27 ||0.17 ||213|
|Pods, South Africa || ||17.3 || 24.8 ||5.7 ||3.1 || 49.1 ||0.79 ||0.34 ||213|
|Seeds, South Africa || ||37.8 ||10.9 || 5.9 ||6.0 || 39.7 ||0.56 ||0.73 ||213|
|Pod husks, South Africa || ||8.7 ||34.3 || 6.2 ||1.6 ||49.2 ||1.10 ||0.14 ||213|
| ||As % of dry matter|
| ||DM ||CP ||CF ||Ash ||EE ||NFE ||Ca ||P ||Ref.|
|Fresh leaves, Sudan ||90.9 ||13.3 ||9.4 ||9.6 ||8.3 ||59.4 ||4.00 ||0.15 ||64|
|Pods, Tanzania ||12.3 ||22.4 ||5.6 ||1.8 ||57.9 ||0.98 ||0.24 ||166|
|Pods, Kenya|| ||17.8 ||17.5 ||8.4 ||1.7 ||54.6 ||1.34 ||0.36 ||129 |
Acacia tortilis (Forsk.) Hayne subsp. spirocarpa (Hochst. ex
A. Rich) Brenan
Medium umbrella-shaped tree 415 m tall, often with several trunks, reduced to
a small wiry shrub less than 1 m tall under extremely arid conditions. Two
types of thorns abound (1) long, straight, and white, and (2) small, hooked,
and brownish. Leaves up to 2.5 cm long with 410 pairs of pinnae, each with ca
15 pairs of minute leaflets. Flowers white, aromatic, in small clusters. Pods
flat, glabrose, coiled into a spring-like array.
Reported from North African and Middle Eastern Centers of Diversity, Umbrella
Thorn, or cvs thereof, is reported to tolerate alkalinity, drought, heat, sand,
slope, and stony soils. It seems to be more frost tolerant than Prosopis
juliflora, still plants less than 2 years old are easily damaged by frost.
Four subspecies are known in different ecological zones: subspecies
tortilisSahel, Middle East; subspecies raddianaSudan, Middle
East, Sahel(2n=104); subspecies spirocarpaEastern Africa, Sudan; and
subspecies heteracanthaSouthern Africa (2n= 52). The different
subspecies seem to have different ecological tolerances, which is important to
consider when choosing a subspecies for plantations. (2n= 52, 104)
Native to much of Africa and the Middle East, this species has been introduced
in many arid parts of the world. Ironically, it grows faster in the Rajastan
Desert of India, where used for charcoal, firewood, and fodder, than in its
native Israel (Kaplan, 1979). In Malawi, this species is already scorned by
the rural public because it is thorny and difficult to work with. It is being
tried for fencings (Nkaonja, 1980).
Deemed the most promising of 56 Acacia species tried at Jodhpur, India.
Probably ranging from Subtropical Desert to Dry through Tropical Desert Scrub
to Very Dry Forest Life Zones, umbrella tree is reported to tolerate annual
precipitation of 1 to 10 dm, estimated annual temperature of 18 to 28°C, and
pH of 6.5 to 8.5. This species tolerates hot, arid climates with temperatures
as high as 50°C subspecies raddiana grows where minimum temperatures
are close to 0°C. It is best adapted to the lowlands. It thrives where
rainfall is up to 1,000 mm. However, it is also extremely drought resistant
and can survive in climates with less than 100 mm annual rainfall with long,
erratic dry seasons. The tree favors alkaline soils. It grows fairly well in
shallow soil, less than 0.25 m deep, though it develops long lateral roots that
can become a nuisance in nearby fields, paths, and roadways. In shallow soil,
the plants remain shrubby and must be widely spaced to allow for their lateral
For good seed germination, seeds should be treated with concentrated sulphuric
acid for 30 minutes (Roy et al, 1973). Artificial regeneration aiming at
large-scale nursery production requires full use of the germination capacity of
the available seeds. This may be achieved by sulfuric acid pretreatment, which
brings about the germination of all viable seeds. Treatment with boiling water
is selective and mainly breaks the dormancy of bruchid-infested seeds, some of
which are no longer able to germinate. Sowing of unripe seeds without
pretreatment may be called for as an emergency measure in case of very severe
infestation, to achieve at least partial success. Prior to storage, seeds
should be fumigated to arrest progressing deterioration of seed viability by
bruchids (Karschon, 1975). NAS (1980a) recommends dipping the seed in hot
water to soak overnight. Seedlings require initial weeding to facilitate
faster growth. Plantations can be spaced at 3 x 3 m.
Firewood harvested as needed, but 10-year rotations are suggested. In Jodhupr,
flower initiation is ca May-June in 3-year old trees, fruits forming in July
but ripening from November through February. Since the tree coppices well,
there is no need to replant after every harvest.
Eleven-year old trees in deep sandy soils at Jodhpur averaged 6.4 m tall and 14
cm DBH. In shallow sandy loams over hardpan at Pali, India, 7-year old trees
(98% survival) averaged 4.8 m tall, and 10 cm DBH. In sanddunes at Barmer,
India, 5-year old trees averaged 3 m tall, 7 cm DBH. An average tree yields 6
kg pods of which 2.6 kg is clean seed. One tree is said to yield 1418 kg pods
and leaves per year in India (Muthana and Arora, 1980). Acacia tortilis
has been reported to yield giraffe forage at 5 MT/ha/yr.
A 12-year-old plantation in India yielded 54 MT fuel , suggest, annual returns
of 4.5 MT, not a bad return for the desert (NAS, 1980a). The heartwood has
calorific value of 4,400 kcals/kg, making superior firewood and charcoal. It
is one of the main firewood and charcoal sources in parts of Africa, e.g.
around Khartoum. Nitrogen-fixing nodules are reported in South Africa and
Bruchids often damage or destroy the seeds, on the tree or after collecting.
Herbivores, tame and wild alike, are liable to graze seedlings and innovations.
Trees attacked by beetles, mimosoid blights, and caterpillars. The wood is
susceptible to termites. In Tanzania, elephants which eat the bark are wiping
out some park populations. In Israel, the native Acacias host several species
(>40) of mostly monophagous insects, whereas on one exotic, Australian
Acacia saligna, only a few polyphagous species occur (Halperin, 1980).
Only Microcerotermes diversus and Kalotermes flavicollis, which
feed on woody parts of both Acacias and Apate monachus (a beetle which
tunnels the stems and branches, causing them to collapse in windblow), may
seriously damage the tree. In nature, regeneration and spread of Acacias are
probably limited by bruchids destroying much of the seed crop. Seedlings from
natural regeneration may come from damaged seeds with a still intact embryo
axis, since seedcoat dormancy is removed by the effect of exit holes permitting
rapid water absorption and germination. Intact seeds with hard impermeable
seedcoats may require a long time to germinate, and probably function as a
reserve to ensure the survival of the species (Karschon, 1975).
|Digestibility (%) |
| ||Animal ||CP ||CF ||EE ||NFE ||ME ||Ref |
|Pods ||Cattle ||46.2 ||42.0 ||74.0 ||76.6 ||2.30 ||166 |
Complete list of references for Duke, Handbook of Energy Crops
- Dalziel, J.M. 1937. The useful plants of west tropical Africa. The Whitefriars
Press, Ltd., London and Tonbridge.
- Gohl, B. 1981. Tropical feeds. Feed information summaries and nutritive values.
FAO Animal Production and Health Series 12. FAO, Rome.
- Halperin, J. 1980. Forest insects and protection in the arid zones of Israel.
J. Israel For. Assoc. 30(3/4):6872.
- Kaplan, J. 1979. Some examples of successful use of Acacia for
afforestation. J. Israel For. Assoc. 29(3/4):6364.
- Karschon, R. 1975. Seed germination of Acacia raddiana Savi and A.
tortilis Rayne as related to infestation by bruchids. Ag. Res. Org. Leaflet
52. Bet Dagan.
- Muthana, K.D. and Arora, G.D. 1980. Performance of Acacia tortilis
(Forsk) under different habitats of the Indian arid zone. Ann. Arid Zone
- N.A.S. 1979. Tropical legumes: resources for the future. National Academy of
Sciences, Washington, DC.
- N.A.S. 1980a. Firewood crops. Shrub and tree species for energy production.
National Academy of Sciences, Washington, DC.
- Nkaonja, R.S.W. 1980. Dryland afforestation problems in Malawi. J. Israel For.
- Palmer, E. and Pitman, N. 1972. Trees of Southern Africa. 3 vols. A.A.
Balkemia, Cape Town.
- Roy, A.D., Kaul, R.N., and Gyanchand. 1973. Israeli babool a promising tree for
arid and semiarid lands.
Last update December 19, 1997