Syn.: Mimosa nilotica L. Mimosaceae "Motse", Egyptian Mimosa, or Thorn
Source: James A. Duke. 1983. Handbook of Energy Crops. unpublished.
Some feel that the thorn bush of Exodus 3 was Acacia nilotica, the fire, the parasite Loranthus
acaciae. Inner bark contains 18–23% tannin, used for tanning and dyeing leather black. Young pods produce a very
pale tint in leather, notably goat hides (Kano leather). Pods were used by the ancient Egyptians. Young bark used as fiber,
twigs esteemed for tooth brushes (chewsticks). Trees tapped for gum arabic. The gum arabic is still used in making candles,
inks, matches, and paints (NAS, 1980). Tender pods and shoots used as vegetable, and used as forage for camels, sheep and
goats, especially in Sudan, where it is said to improve milk from these animals. Seeds are a valuable cattle food. Roasted
seed kernels, sometimes used for flavoring and when crushed provide the dye for black strings worn by Nankani women. Trees
used in Sudan for afforestation of inundated areas. Sapwood is yellowish-white, heartwood reddish-brown, hard, heavy, durable,
difficult to work, though taking a high polish. Because of its resins, it resists insects and water, and trees are harvested
for the timber for boat-making, posts, buildings, water-pipes, well-planking, plows, cabinet-work, wheels, mallets and other
implements. Wood yields excellent firewood and charcoal (Duke, 1981a). The aqueous extract of the fruit, rich in tannin (18–23%)
has shown algicidal activity against Chroccoccus, Closteruim, Coelastrum, Cosmarium, Cyclotella, Euglena, Microcystis,
Oscillatoria, Pediastrum, Rivularia, Spirogyra, and Spirulina (Ayoub, 1983).
Zulu take bark for cough, Chipi use root for tuberculosis. Masai are intoxicated by the bark and
root decoction, said to impart courage, even aphrodisia, and the root is said to cure impotence. Astringent bark used for
diarrhea, dysentery, and leprosy. Bruised leaves poulticed onto ulcers. According to Hartwell, the gum or bark is used for
cancers and/or tumors (of ear, eye, or testicles) and indurations of liver and spleen, condylomas, and excess flesh. Said
also to be used for cancer, colds, congestion, coughs, diarrhea, dysentery, fever, gallbladder, hemorrhage, hemorrhoids, leucorrhea,
ophthalmia, sclerosis, smallpox, and tuberculosis. Bark, gum, leaves, and pods used medicinally in West Africa. Sap or bark,
leaves, and young pods are strongly astringent due to tannin, and are chewed In Senegal as antiscorbutic; in Ethiopia as lactogogue.
Bark decoction drunk for intestinal pains and diarrhea. Other preparations used for coughs, gargle, toothache, ophthalmia,
and syphilitic ulcers. In Tonga, the root is used to treat tuberculosis. In Lebanon, the resin is mixed with orange-flower
infusion for typhoid convalescence. Masai use the bark decoction as a nerve stimulant. In Italian Africa, the wood is used
to treat smallpox. Egyptian Nubians believe that diabetics may eat unlimited carbohydrates as long as they also consume powdered
pods (Duke, 1983a). Extracts are inhibitory to at least four species of pathogenic fungi (Umalkar et al, 1976).
Babul has been reported to contain l-arabinose, catechol, galactan, galactoaraban, galactose,
N-acetyldjenkolic acid, N-acetyldjenkolic acid, sulphoxides pentosan, saponin, tannin. Seeds contain crude protein 18.6%,
ether extract 4.4%, fiber 10.1%, nitrogen-free extract 61.2%, ash 5.7%, and silica 0.44%. Phosphorus 0.29% and calcium 0.90%
of DM. When bullocks were given the seeds and bran (2:1) with dry pasture grass daily DM intakes were 1.82, 0.91, and 5.35
kg respectively. Total DM intake/100 kg bodyweight was 1.40 kg. The animals retained 20.8 g N and 7.4 g Ca daily but the P
balance was slightly negative (Pande et al, 1981). Walker (1980) puts the CP content of the browse at 12.9%, the crude fiber
at 15.2%
Small tree, 2.5–14 m tall, quite variable in many aspects; bark of twigs not flaking off,
gray to brown; branches spreading, with flat or rounded crown; bark thin, rough, fissured, deep red-brown; branchlets purple-brown,
shortly or densely gray-pubescent, with lenticels; spines gray-pubescent, slightly recurved, up to 3 cm long; leaves often
with 1–2 petiolar glands and other glands between all or only the uppermost pinnae; plnnae 2–11 (-17) pairs; leaflets
7–25 (-30) pairs, 1.5–7 mm long, 0.5–1.5 mm wide, glabrous or pubescent, apex obtuse; peduncles clustered
at nodes of leafy and leafless branchlets; flowers bright yellow, in axillary heads 6–15 mm in diam.; involucel from
near the base to about half-way up the peduncle, rarely somewhat higher; calyx 1–2 mm long, subglabrous to pubescent;
corolla 2.5–3.5 mm long, glabrous or pubescent outside; pods especially variable, linear, indehiscent, 8–17 (-24)
cm long, 1.3–2.2 cm broad, straight or curved, glabrous or gray-velvety, turgid, blackish, about 12-seeded; seeds deep
blackish-brown, smooth, subcircular, compressed, areole 6–7 mm long, 4.5–5 mm wide. Fl. Oct.–Dec.; fr. Mar.–June
(Duke, 1981a).
Acacia nilotica var. kraussiana (Benth.) Brenan is the most common form in east
tropical Africa. Young branches more or less densely pubescent; pods not necklace-like, 1–1.8 cm wide, oblong, more
or less pubescent all over at first with raised parts over seeds becoming glabrescent, shining and black when dry, margins
shallowly crenate. Exhibits wide range of altitudinal and habitat requirements. Found in Botswana, Zambia, Rhodesia, Malawi,
Tanzania, Angola, Mozambique, Transvaal, and Natal. A.nilotica var. tomentosa A. F. Hill (A. arabica
var. tomentosa Benth.), has pods straight, constricted between seeds and densely tomentose; found in Senegal and northern
Nigeria, to Sudan, Arabia and India. A. nilotica var. adansonii (Guill. et Perr.) Kuntze is a tree up to 17
m with dark reddish-brown bark deeply fissured, tomentose, reddish-brown twigs and gray fruits; commonest variety in West
Africa, from Senegal to Nigeria and widespread in northern parts of Tropical Africa. Assigned to the African Center of Diversity,
babul or cvs thereof is reported to exhibit tolerance to clay, drought, heat, heavy soil, high pH, poor soils, salt, savanna,
and waterlogging. (2n=52.)
DESCRIPTION
Native from Egypt south to Mozambique and Natal; apparently introduced to Zanzibar, Pemba, and
India; Arabia. Considered a serious weed in South Africa.
Woodlands of various sorts, wooded grasslands, scrub and thickets. Thrives in dry areas, but endures
floods. Grows 10–1,340 m altitude, in a wide range of conditions. Grows on a wide variety of soils, seemingly thriving
on alluvial soils, black cotton soils, heavy clay soils, as well as even poorer soils (NAS, 1980). Ranging from Subtropical
Desert to Subtropical Dry through Tropical Desert to Tropical Dry Forest Life Zones, babul is reported to tolerate annual
precipitation of 3.8–22.8 dm (mean of 12 cases = 12.0 dm), annual mean temperature of 18.7–27.8°C (mean of 12
cases = 24.1°C), and pH of 5.0–8.0 (mean of 10 cases = 6.9) (Duke, 1981a).
Trees propagated in forest by seeds. Direct seeding is the common practice. Stored seed may require
scarification. Young seedlings are said to "require full sun and frequent weeding" (NAS, 1980a).
Although there are other sources of gum arabic, trees are still tapped for the gum by removing
a bit of bark 5–7.5 cm wide and bruising the surrounding bark with mallet or hammer. The resulting reddish gum, almost
completely soluble and tasteless, is formed into balls. Though used in commerce to some extent, it is inferior to other forms
of gum arabic, with which it is sometimes mixed.
YIELD AND ECONOMICS
Various products of the tree are used locally in tropical Africa, but none enter international
markets. Trees usually add 2–3 cm in diameter each year (NAS, 1980a).
Energy
Extensively used, e.g. in India, for firewood and charcoal, this species has been used in locomotives
and steamships as well as industry balers. It is cultivated for industrial fuel in the Sudan. The calorific value of the sapwood
is 4,800 kcal/kg of the heartwood 4,950. The species does nodulate and fix nitrogen.
Wood borers may afflict the stems and bruchids may afflict the seeds. Following fungi have been
reported on this plant: Ctyospora acaciae, Diatryphe acaciae, Diplodia acaciae, Fomes badius, F. endotheius, F. fastuosus,
F. rimosus, Fusicoccum indicum, Phyllactinia acaciae, Ravenelia acaciae-arabicae,Septogloeum acaciae, Septoria mortolensis,
Sphaerostilbe acaciae. Trees are also parasitized by Dendrophthoe falcata and Loranthus globiferus var.
verrucosus (Duke, 1981). In a survey for phytophagous insects on Acacia nilotica, 43 species were recorded in
Pakistan, of these, 16 appeared stenophagous. The more promising for biological control of the tree were: Anarsia sp.
cf. acaciae, Pseudosterrhapaulula, Azanus ubaldus, and Ceutholopha isidis feeding on flowers;
Bruchidiussahlbergi and Sulcobruchus sp. damaging seeds; Ascalenia callynella, Gisilia stereodoxa
and an unidentified gracillariid boring shoots; and Cydia sp. making stem galls (Mohyuddin, 1981).
Ayoub, S.M.H. 1983. Algicidal properties of Acacia nilotica. Fitoterapia 53(5–6):175–8.
Duke, 1981.
Duke, J.A. 1981a. Handbook of legumes of world economic importance. Plenum Press. NewYork.
Duke, J.A. 1983a. Medicinal plants of the Bible. Trado-Medic Books, Owerri, NY.
Mohyuddin, A.I. 1981. Phytophages associated with Acacia nilotica in Pakistan and possibilities
of their introduction into Australia. p. 161–166. Proceedings of the 5th International Symposium on Biological Control
of Weeds. Australia Commonwealth Scientific and Industrial Research Organization.
N.A.S. 1980a. Firewood crops. Shrub and tree species for energy production. National Academy of
Sciences, Washington, DC.
Pande, M.B., Talpada, P.M., Patel, J.S., and Shukla, P.C. 1981. Note on the nutritive value of
babul (Acacia nilotica L.) seeds (extracted). In: Indian J. Anim. Sci. 51(1):107–108.
Umalkar, C.V., Begum, S., Nehemiah, K.M.A. 1976. Inhibitory effect of Acacia nilotica extracts
on pectolytic enzyme production by some pathogenic fungi. Indian Phytopath.: publ. 1977, 29(4):469–470.
Walker, B.H. 1980. A review of browse and its role in livestock production in southern Africa.
p. 7–24. In: LeHouerou, H.N. (ed.), Browse in Africa. International Livestock Centre for Africa. Addis Ababa, Ethiopia.
A
variable and widely used tree from Africa and the Indian subcontinent. Subsp. indica, introduced to northern Australia,
has spread into dry grassland, slowly at first, but then with population explosions during wet years.
Species characteristics
Life form, size, lifespan
Thorny small tree growing to a height
of 7 m. Lives at least 60 years.
Taxonomy, variation and plasticity
Nine
sub-species are recognised. Hybridization between the various ssp. occurs and has been influenced by human's seed dispersal.
Within the A. nilotica complex the pods are very variable.
Reproductive biology
The yellow sweetly scented flowers are
nectarless and found in round heads. Most flowers are functionally male with a few hermaphrodites and are mainly bee-pollinated.
Pods are indehiscent. Seed production is high (up to 175,000 seeds/tree) and yearly provided water is plentiful like along
water courses. In Kenya seed set per pod was 10.8 and trees produced between 153 and 34,000 seeds. It forms large seedbanks
and in Australia the half-life of seeds is 10-12 months.
Leaf
production and fall are affected by rainfall whereas temperature affect flowering and fruiting. In Sudan A. nilotica
flowers irregularly but generally between June and September and seed fall takes place from march to May. In Australia trees
flower from March to June and green pods are produced within four months but ripe pods fall from November to February. Most
of the leaf fall occurs during the dry period when the tree bears green pods.
Resilience and resistance
Species
is sensitive to frost but is tolerant of grazing, drought (< 2 years), fire and salinity.
Environmental requirements and successional
status
Requires
water for seed germination and seedling establishment. Can regenerate under pioneer woody plants in seasonally flooding habitats
and subsequently outcompete them.
Products and uses
Extensively
used as browse, firewood and timber. The bark and seeds are a source of tannin while bark, roots and flowers are used for
medicinal properties. The gum is sometimes used. The wood is suitable for paper production. Planted for forestry or reclamation
of degraded land.
Status in native range
Range and abundance
Native
to India, Pakistan and much of Africa where it is often dominant.
Climate
Grows
in areas where the mean monthly temperature of the coldest month is above 16°C. It tolerates a wide range of rainfall
from less than 350 mm to more than 1500 mm or more per year.
Site requirements
A.
nilotica subsp. indica is commonly found on soils with a high clay content, but in areas of higher rainfall it
may grow on deep sandy loam. Often found growing close to waterways on seasonally flooded river flats. In Sudan, along the
Nile, regeneration has been reported as occurring once every ca. 15 years following high floods.
Weediness
With
the exception of A. nilotica spp. kraussiana in southern Africa, there does not appear to be much evidence to
show that the tree is weedy in its native range.
Pests and diseases
Many
wild mammals feed on seed pods and a large number of insect species attack the mature seed.
Status in invaded regions
History of introductions and intensity of
invasions
A.
nilotica subsp. indica, native to the region spanning from Ethiopia to Burma, was introduced to Iran, Vietnam,
the Caribbean and Australia. Introduced to Australia around 1900 as a shade tree along bore drains in Queensland. Found elsewhere
in Australia but the distribution is limited by frost. Around 1960 it was found in 7% of the Mitchell grassland areas and
by the mid 1980s it covered 6.6 million ha or 25% of the area. Its distribution and population densities are still increasing.
Since 1969 introduced to the Baluran National Park (Java, Indonesia) as a firebreak and is spreading vigorously.
Patterns of invasion and time-lag
Dramatic
increase in A. nilotica, particularly on town commons, took place in the 1950s as a result of a series of years with
above average rainfall. Following this population outbreak the species was declared a noxious weed. Instead or removing the
plant as required, many landholders continued to plant them along open drains distributing artesian water. The constant water
supply ensured fast grow rates and the production of large seed crops, which were spread by cattle throughout the surrounding
countryside forming large seedbanks. During a second period of above average rainfall in the mid-1970s germination of the
seedbank occurred and resulted in a 1000 fold increase in A. nilotica populations. The highest densities of A. nilotica
are found on properties which had the tree planted along its drains prior to the 1970s and had cattle rather than sheep grazing.
In the 1980s a prolonged drought has reduced tree density in some areas by up to 80%. In Indonesia it invaded, with apparently
no time-lag, wild grasslands.
Site and climate
Clay
soils in dry tropics.
Floristic region and vegetation types
In
northern Australia, A. nilotica is spreading into grassland dominated by Astrebla spp.
Pests and diseases
Two
insect species, including one Coleoptera introduced as an attempt at biological control, eat the seeds unless they are quickly
ingested by mammals soon after ripening. The passage through the digestive track of cattle apparently make seeds nearly immune
to insect attack.
Impact on ecosystem
The
vast grasslands of northern Australia are changed into woodland. In Indonesia it is altering the physiognomy of the invaded
ecosystem and depriving native mammals of grazing grounds.
Impact on humans and related activities
The
invasion reduces the livestock carrying capacity of Queensland's Mitchell grasslands. It may have an impact on the number
of tourists frequenting the Baluran National Park as most visit the park to view large herds of herbivores.
Control
In
Indonesia both mechanical and chemical control have been practised and the former was found to be more economical. In Australia
a biological control programme has been initiated.
A quick guide to useful nitrogen fixing trees from around the world
Acacia nilotica
( pioneer for Dry Lands)
Acacia nilotica (L.) Willd. ex Del. (Leguminosae, subfamily Mimosoideae) is one of about 135 thorny African Acacia
species. Variation is considerable with nine subspecies presently recognized, three occurring in the Indian subcontinent and
six throughout Africa (Brenan 1983.) They are distinguished by the shape and pubescense of pods and the habit of the tree.
Botany In habit A. nilotica varies from a shrubby tree with wide spreading crowns
in savanna habitats (ssp. subalata, leiocarpa, adstringens, hemispherica and kraussiana), to a 20 meter tree
(ssp. nilotica, tomentosa, and indica) in riverine situations. Ssp. cupressiformis has ascending branches
like a poplar.
Acacia nilotica is easy to recognize by its bright yellow flowers in round heads, straight stipular spines often
slightly deflexed, and dark indehiscent pods compressed over the seeds. Flowering is prolific, and can occur a number of times
in a season. Often only about 0.1% of flowers set pods (Tybirk 1989.) The taxa form a polyploid complex most are tetraploids
(2n=4x=52); but higher numbers have been found in ssp. nilotica (2n=8x=104) & ssp. tomentosa (2n=16x=208)
(Nongonierma 1976.)
ECOLOGY There are two very distinct ecological preferences in the African subspecies. Subspecies subalata,
leiocarpa and adstringens occur in wooded grassland, savanna and dry scrub forests. Subspecies nilotica
and tomentosa are restricted to riverine habitats and seasonally flooded areas. Subspecies kraussiana prefers
dry grasslands and savannas, especially on compacted sandy loam, shallow granite or clay soils along drainages and rivers,
but away from flooding.
On the subcontinent, ssp. indica forms low altitude dry forests usually on alluvium and black cotton soils. It has
been widely planted on farms throughout the plains of the subcontinent. The species grows on saline, alkaline soils, and on
those with calcareous pans. Subspecies hemispherica is restricted to dry sandy streams beds near Karchi, ssp. cupressiformis
has similar preferences to ssp. indica though is less resilient to weed competition.
A. nilotica occurs from sea level to over 2000 m. It withstands extremes of temperature (-1 to 50?C), but is frost
tender when young. Annual rainfall varies from 250 - 1500 mm. Trees are generally deciduous during the dry season, though
riverine ssp. can be almost evergreen.
Distribution The species is naturally widespread in the drier areas of Africa, from Senegal to Egypt and down
to South Africa, and in Asia from Arabia eastwards to India, Burma and Sri Lanka. It has also been cultivated elsewhere, including
Australia, Cape Verde islands, Indonesia, Iran, Iraq, Nepal, Vietnam, and the West Indies.
USES. Wood. Since the time of the Pharoahs, large timber trees have been exploited from the riverine
forests of the Nile. At present the Sudan forests are managed on a 20-30 year rotation producing termite resistant timber
especially suitable for railway sleepers. In India and Pakistan riverine plantations are managed on a 15-20 year rotation
for fuelwood and timber.
The dark brown wood is strong, durable, nearly twice as hard as teak, very shock resistant, and is used for construction,
mine props, tool handles and carts. It is best carved in a green state. It has a high calorific value of 4950 kcal/kg, making
excellent fuelwood and quality charcoal. It burns slow with little smoke when dry.
Fodder. The pods and leaves contain 8% digestible protein [12.4% crude protein], 7.2 MJ/kg energy, and are rich
in minerals (Le Houerou 1980). In part of its range smallstock mainly consume it, but elsewhere it is also very popular with
cattle. Pods are used as a supplement to poultry rations in India. Dried pods are particularly sought out by animals on rangelands.
In India branches are commonly lopped for fodder. Pods are best fed dry as a supplement, not as a green fodder.
Agroforestry. Babul (ssp. indica) is a popular farm tree of the central plains of India. More recently interest
has centred on the fastigiate form (ssp. cupressiformis). This subspecies makes an ideal windbreak surrounding fields;
its narrow crown shades less than other windbreak species.
Land Rehabilitation. In India this species is used extensively on degraded saline/alkaline soils, growing on soils
up to pH 9, with a soluble salt content below 3%. It also grows well when irrigated with tannery effluent, and colonises waste
heaps from coal mines. Over 50,000 hectares of the Indian Chambal ravines have been rehabilitated with A. nilotica
by aerial seeding (it is one of the 3 most frequently used trees for this purpose).
Tannins. The bark of ssp. indica has high levels of tannin (12-20%) which are used for tanning leathers.
Ten year old trees yield 35-40 kg of bark. The pods of ssp. nilotica have been used for tanning in Egypt for 6,000
years. Subspecies adstringens is used for both tanning and dye making. Deseeded pods from ssp. indica have 18-27%
tannin levels, whereas ssp. tomentosa and nilotica reach up to 50%.
Other Uses. The tannin also contributes to its medicinal use as a powerful astringent. It is also a powerful molluscicide
and algicide. Fruits added to ponds in Sudan kill snail species which carry schistosomiasis without affecting the fish.
There are many other reported uses (Fagg & Greaves 1990). The tree makes effective live fencing, a good host plant
for growing sandalwood, and an important source shellac in the Sind. The gum is used in paints and medicines and has been
collected for a millennia. It has similar properties to gum arabic (from A. senegal) and is frequently used in calico
printing in India.
SILVICULTURE.Propagation. It is a pioneer species, easily regenerated from seed. The nutritious indehiscent
pods have evolved for animal dispersal. A mature tree can produce 2,000-3,000 pods in a good fruiting season, each with 8-16
seeds, yielding 5,000 - 16,000 seed/kg depending on the subspecies.
Hard coated seeds can be extracted by pounding the pods or collected from animal pens after the pods have been eaten (Sheikh
1989). Pretreatment is needed. Mechanical scarification works best for small seed lots. Acid scarification from 60 - 120 minutes
(depending on seed provenance or age), or pouring boiling water over the seeds and allowing them to cool are also effective.
Seed from natural populations of some subspecies are available from India and some Sahelian countries. A broader range
of germplasm and Rhizobium inoculum, is available from the Oxford Forestry Institute (Oxford OX1 3RB UK) for field
trials.
Management The species can be direct seeded or established by seedlings. in the nursery long poly tubes (20 x 7
cm) should be used so as not to restrict rapid tap root growth. Frequent root pruning is advised. Nursery grown seedlings
are usually outplanted after 6 months, but in some cases stay in the nursery up to a year.
Establishment varies depending on the site. Seedlings are shade intolerant. In irrigated plantations in the Sind and Punjab,
10-15 seeds are spot sown at 2x3 m spacing on the tops of trenches. They are thinned to 3-4 seedlings after 3-4 months. Further
thinning occurs at 5 year intervals. Rotations are 20-25 years. In the Thal desert, Pakistan (250 mm of rain), promising growth
resulted from irrigation on a 10 day interval. Growth rates varied considerably depending on the sites, with maximum mean
annual increment of 13 m3 /ha at 20 yrs old and 10.5 m3 /ha at 30 years recorded.
LIMITATIONS. A wide range of pests and diseases affect this species. Of economic importance is the stem borer Cerostema
scabrator on young plantations in India. Euproctis lunata & E. subnotata occasionally defoliate patches
of forest in Sukkur and Hyderabad. Bruchid beetles attack the seeds, destroying up to 70 %. Buprestid beetles cause a dieback
disease in Sudan. Fungal rots (Fomes papianus & F. badius) attack unhealthy trees, and powder post beetles (Sibixylon
anale & Lyctus africanus) attack the sapwood of felled timber.
Acacia nilotica can become weedy when introduced out of its native range, particularly in more humid zones. Thorniness
can be a problem when introduced to areas where people do not traditionally use thorn trees.
PRINCIPAL REFERENCES:
Brenan, J.P.M. 1983. Manual on the taxonomy of Acacia species: Present taxonomy of four species of Acacia (A. albida,
A. senegal, , A. tortilis). FAO, Rome, Italy. 47 p.
Fagg, C.W. and A. Greaves.1990. Acacia nilotica 1869-1988. CABI/OFI Annotated bibliography No. F42. CAB International,
Wallingford, Oxon, UK 77 p.
Le Houerou, H.N. 1980. Chemical composition and nutritional value of browse in tropical West Africa. In H.N. Le Houerou
(ed), Browse in Africa, the Current State of Knowledge. ILCA, Ethiopia. p 261-289.
Nongonierma, A. 1976. Contribution a l'etude du genre Acacia Miller en Afrique occidentale. H. Caracteres des inflorescences,
et des fleurs. Bulletin de l'IFAN Serie A. 38 (3) 487-657.
Tybirk, K 1989. Flowering, pollination, seed production of Acacia nilotica. Nordic Journal of Botany 9 (4) 375-381.
Sheik, M.I. 1989. Acacia nilotica (L.) Willd. ex Del. Its production, Management and Utilization. Pakistan. Regional
wood energy development programme in Asia, GCP/RAS/111/NET Field document no. 20, FAO, Bankok 10200, Thailand. 45 p.
Written by Christopher W. Fagg, Department of Plant Sciences, University of Oxford, Oxford OX1 3RB, UK.
A publication of the Forest, Farm, and Community Tree Network (FACT Net)
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