Acacia
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Acacia
Acacia greggii
Scientific classification
Kingdom: Plantae Division: Magnoliophyta Class: Magnoliopsida Order: Fabales Family: Fabaceae Subfamily: Mimosoideae Tribe: Acacieae Genus: Acacia Miller
Species
About 1,300; see List of Acacia species

Acacia is a genus of shrubs and trees belonging to the subfamily Mimosoideae of the family Fabaceae, first described in Africa by the Swedish botanist Carolus Linnaeus in 1773. The plants tend to be thorny and pod-bearing. The name derives from ακις (akis) which is Greek for a sharp point, due to the thorns in the type-species Acacia nilotica from Egypt. ¹

Acacias are also known as thorntrees or wattles, including the yellow-fever acacia and umbrella acacias.

There are roughly 1300 species of Acacia worldwide, about 960 of them native to Australia, with the remainder spread around the tropical to warm-temperate regions of both hemispheres, including Africa, southern Asia, and the Americas.

Classification

Acacia berlandieri

Acacia pycnantha

The genus Acacia is apparently not monophyletic. This discovery has led to the breaking up of Acacia into five new genera as discussed in list of Acacia species. In common parlance the term "acacia" is occasionally misapplied to species of the genus Robinia, which also belongs in the pea family. Robinia pseudoacacia, an American species locally known as Black locust, is sometimes called "false acacia" in cultivation in the United Kingdom.

Geography

Acacia smallii

Acacia retinodes

The southernmost species in the genus are Acacia dealbata (Silver Wattle), Acacia longifolia (Coast Wattle or Sydney Golden Wattle), Acacia mearnsii (Black Wattle), and Acacia melanoxylon (Blackwood), reaching 43°30' S in Tasmania, Australia, while Acacia caven (Espinillo Negro) reaches nearly as far south in northeastern Chubut Province of Argentina. Australian species are usually called wattles, while African and American species tend to be known as acacias.

Acacia albida, Acacia tortilis and Acacia iraqensis can be found growing wild in the Sinai desert and the Jordan valley. It is found in the savanna vegetation of the tropical continental climate.

Description

Acacia dealbata

The leaves of acacias are compound pinnate in general. In some species, however, more especially in the Australian and Pacific islands species, the leaflets are suppressed, and the leaf-stalks (petioles) become vertically flattened, and serve the purpose of leaves. These are known as phyllodes. The vertical orientation of the phyllodes protects them from intense sunlight, as with their edges towards the sky and earth they do not intercept light so fully as horizontally placed leaves. A few species (such as Acacia glaucoptera) lack leaves or phyllodes altogether, but possess instead cladodes, modified leaf-like photosynthetic stems functioning as leaves.

The small flowers have five very small petals, almost hidden by the long stamens, and are arranged in dense globular or cylindrical clusters; they are yellow or cream-colored in most species, whitish in some, even purple (Acacia purpureapetala) or red (Acacia leprosa Scarlet Blaze).

The plants often bear spines, especially those species growing in arid regions. These sometimes represent branches which have become short, hard and pungent, or sometimes leaf-stipules. Acacia armata is the Kangaroo-thorn of Australia and Acacia erioloba is the Camelthorn of Africa.

Symbiosis

Acacia collinsii Thorns

In the Central American Acacia sphaerocephala, Acacia cornigera, and Acacia collinsii (collectively known as the bullthorn acacias), the large thorn-like stipules are hollow and afford shelter for ants, which feed on a secretion of sap on the leaf-stalk and small, lipid-rich food-bodies at the tips of the leaflets called Beltian bodies; in return they add protection to the plant against herbivores.² Some species of ants will also fight off competing plants around the acacia, cutting off the offending plant's leaves with their jaws and ultimately killing it, while other ant species will do nothing to benefit their host.

Pests

Acacia tree near the end of its range in the Negev Desert of southern Israel.

In Australia, Acacia species are sometimes used as food plants by the larvae of hepialid moths of the genus Aenetus including A. ligniveren. These burrow horizontally into the trunk then vertically down. Other Lepidoptera larvae which have been recorded feeding on Acacia include Brown-tail, Endoclita malabaricus and Turnip Moth. The leaf-mining larvae of some bucculatricid moths also feed on Acacia: Bucculatrix agilis feeds exclusively on Acacia horrida and Bucculatrix flexuosa feeds exclusively on Acacia nilotica.

Acacias contain a number of organic compounds that defend them from pests and grazing animals.³

Uses

Food uses

Acacia seeds are often used for food and a variety of other products.

In Burma, Laos and Thailand, the feathery shoots of Acacia pennata (common name cha-om, ชะอม and su pout ywet in Burmese) are used in soups, curries, omelettes, and stir-fries.

Honey made by bees using the acacia flower as forage is considered a delicacy, appreciated for its mild flowery taste, soft running texture and glass-like appearance. Acacia honey is one of the few honeys which does not crystallize.⁴
In Mexico the seeds are known as Guajes: Guajes or huajes are the flat, green pods of an acacia tree. The pods are sometimes light green or deep red in color -- both taste the same. Guaje seeds are about the size of a small lima bean and are eaten raw with guacamole, sometimes cooked and made into a sauce. They can also be made into fritters. The ground seeds are used to impart a slightly garlicy flavor to a mole called guaxmole (huaxmole). The dried seeds may be toasted and salted and eaten as a snack referred to as "cacalas". Purchase whole long pods fresh or dried at Mexican specialty markets.

Acacia is listed as an ingredient in Fresca, a citrus soft drink, Barq's root beer, Full Throttle Unleaded Energy Drink, Strawberry-Lemonade POWERade⁵ as well as in Läkerol pastille candies, Altoids mints, and Wrigley's Eclipse chewing gum.

Gum

Various species of acacia yield gum. True gum arabic is the product of Acacia senegal, abundant in dry tropical West Africa from Senegal to northern Nigeria.

Acacia arabica is the gum-Arabic tree of India, but yields a gum inferior to the true gum-Arabic.

Acacia covenyi

Medicinal uses

Many Acacia species have important uses in traditional medicine. Most all of the uses have been shown to have a scientific basis, since chemical compounds found in the various species have medicinal effects. In Ayurvedic medicine, Acacia nilotica is considered a remedy that is helpful for treating premature ejaculation. A 19th century Ethiopian medical text describes a potion made from an Ethiopian species of Acacia (known as grar) mixed with the root of the tacha, then boiled, as a cure for rabies.⁶ An astringent medicine, called catechu or cutch, is procured from several species, but more especially from Acacia catechu, by boiling down the wood and evaporating the solution so as to get an extract.⁷

Ornamental uses

A few species are widely grown as ornamentals in gardens; the most popular perhaps is Acacia dealbata (Silver Wattle), with its attractive glaucous to silvery leaves and bright yellow flowers; it is erroneously known as "mimosa" in some areas where it is cultivated, through confusion with the related genus Mimosa.

Another ornamental acacia is Acacia xanthophloea (Fever Tree). Southern European florists use Acacia baileyana, Acacia dealbata, Acacia pycnantha and Acacia retinodes as cut flowers and the common name there for them is mimosa.⁸

Ornamental species of acacia are also used by homeowners and landscape architects for home security. The sharp thorns of some species deter unauthorized persons from entering private properties, and may prevent break-ins if planted under windows and near drainpipes. The aesthetic characteristics of acacia plants, in conjunction with their home security qualities, makes them a considerable alternative to artificial fences and walls.

Paints

The ancient Egyptians used Acacia in paints.⁹

Perfume

Acacia farnesiana

Acacia farnesiana is used in the perfume industry due to its strong fragrance. The use of Acacia as a fragrance dates back centuries. In The Bible, burning of acacia wood as a form of incense is mentioned several times.

Symbolism and ritual

The Acacia is used as a symbol in Freemasonry, to represent purity and endurance of the soul, and as funerary symbolism signifying resurrection and immortality.

Several parts (mainly bark, root and resin) of Acacia are used to make incense for rituals. Acacia is used in incense mainly in India, Nepal, Tibet and China. Smoke from Acacia bark is thought to keep demons and ghosts away and to put the gods in a good mood. Roots and resin from Acacia are combined with rhododendron, acorus, cytisus, salvia and some other components of incense. Both people and elephants like an alcoholic beverage made from acacia fruit.¹⁰ According to Easton's Bible Dictionary, the Acacia tree may be the “burning bush” (Exodus 3:2) which Moses encountered in the desert.¹¹ Also, when God gave Moses the instructions for building the Tabernacle, he said to "make an ark of acacia wood" and "make a table of acacia wood" (Exodus 25:10 & 23, Revised Standard Version)

Tannin

A bottle of tannic acid.

The bark of various Australian species, known as wattles, is very rich in tannin and forms an important article of export; important species include Acacia pycnantha (Golden Wattle), Acacia decurrens (Tan Wattle), Acacia dealbata (Silver Wattle) and Acacia mearnsii (Black Wattle).

*Inner bark

Black Wattle is grown in plantations in South Africa. Most Australian acacia species introduced to South Africa have become an enormous problem, due to their naturally aggressive propagation. The pods of Acacia nilotica (under the name of neb-neb), and of other African species are also rich in tannin and used by tanners.

Wood

Acacia koa Wood

Most acacia species are used for valuable timber; such are Acacia melanoxylon (Blackwood) from Australia, which attains a great size; its wood is used for furniture, and takes a high polish; and Acacia omalophylla (Myall Wood, also Australian), which yields a fragrant timber, used as ornament. Acacia seyal is thought to be the Shittah-tree of the Bible, which supplied shittim-wood. According to the Book of Exodus, this was used in the construction of the Ark of the Covenant. Acacia koa from the Hawaiian Islands and Acacia heterophylla from Réunion island are both excellent timber trees.

Acacia heterophylla Wood

In Indonesia (mainly in Sumatra) and in Malaysia (mainly in Sarawak) plantations of Acacia mangium are being established to supply pulpwood to the paper industry.

Phytochemistry of Acacia

Alkaloids

Egyptian goddess Isis

As mentioned previously, Acacias contain a number of organic compounds that defend them from pests and grazing animals.³ Many of these compounds are psychoactive in humans. The alkaloids found in Acacias include dimethyltryptamine (DMT), 5-methoxy-dimethyltryptamine (5-MeO-DMT) and N-methyltryptamine (NMT). The plant leaves, stems and/or roots are sometimes made into a brew together with some MAOI-containing plant and consumed orally for healing, ceremonial or religious uses. Egyptian mythology has associated the acacia tree with characteristics of the tree of life (cf. article on the Legend of Osiris and Isis).

Acacias Known to Contain Psychoactive Alkaloids

Acacia acuminata	Up to 1.5% alkaloids, mainly consisting of tryptamine in leaf18
Acacia adunca	β-methyl-phenethylamine, 2.4% in leaves19
Acacia alpina	Active principles in leaf20
Acacia aneura	Ash used in Pituri.21 Ether extracts about 2-6% of the dried leaf mass.22 Not known if psychoactive per se.
Acacia angustissima	β-methyl-phenethylamine23, NMT and DMT in leaf (1.1-10.2 ppm)24
Acacia aroma	Tryptamine alkaloids.25 Significant amount of tryptamine in the seeds.26
Acacia auriculiformis	5-MeO-DMT in stem bark27
Acacia baileyana	0.02% tryptamine and β-carbolines, in the leaf, Tetrahydroharman202829
Acacia beauverdiana	Psychoactive30 Ash used in Pituri.21
Acacia berlandieri	DMT, amphetamines, mescaline, nicotine31
Acacia catechu	DMT32 and other tryptamines in leaf, bark
Acacia caven	Tryptamines
Acacia chundra	DMT and other tryptamines in leaf, bark
Acacia colei	DMT33
Acacia complanata	0.3% alkaloids in leaf and stem, almost all N-methyl-tetrahydroharman, with traces of tetrahydroharman, some of tryptamine343536
Acacia concinna	Nicotine37
Acacia confusa	DMT & NMT in leaf, stem & bark 0.04% NMT and 0.02% DMT in stem.20 Also N,N-dimethyltryptamine N-oxide38
Acacia constricta	β-methyl-phenethylamine23
Acacia coriacea	Ash used in Pituri.3921 Not known if psychoactive.
Acacia cornigera	Psychoactive,39 Tryptamines10
Acacia cultriformis	Tryptamine, in the leaf, stem20 and seeds.26 Phenethylamine in leaf and seeds26
Acacia cuthbertsonii	Psychoactive30
Acacia delibrata	Psychoactive30
Acacia falcata	Psychoactive,30 but less than 0.02% alkaloids29
Acacia farnesiana	Traces of 5-MeO-DMT40 in fruit. β-methyl-phenethylamine, flower.41 Ether extracts about 2-6% of the dried leaf mass.22 Alkaloids are present in the bark42 and leaves.43 Amphetamines and mescaline also found in tree.10
Acacia filiciana	Added to Pulque, but not known if psychoactive39
Acacia floribunda	Tryptamine, phenethylamine,44 in flowers26 other tryptamines,45 phenethylamines46
Acacia greggii	N-methyl-β-phenethylamine,23 phenethylamine3
Acacia harpophylla	Phenethylamine, hordenine at a ratio of 2:3 in dried leaves, 0.6% total19
Acacia holoserica	Hordenine, 1.2% in bark19
Acacia horrida	Psychoactive39
Acacia implexa	Psychoactive47
Acacia jurema	DMT, NMT
Acacia karroo	Psychoactive
Acacia kempeana	Used in Pituri, but not known if psychoactive.39
Acacia kettlewelliae	1.519-1.88%48 alkaloids, 92% consisting of phenylethylamine.19 0.9% N-methyl-2- phenylethylamine found a different time.19
Acacia laeta	DMT, in the leaf20
Acacia lingulata	Used in Pituri, but not known if psychoactive.39
Acacia longifolia	0.2% tryptamine in bark, leaves, some in flowers, phenylethylamine in flowers,44 0.2% DMT in plant.49 Histamine alkaloids.29
Acacia longifolia var. sophorae	Tryptamine in leaves, bark26
Acacia macradenia	Tryptamine26
Acacia maidenii	0.6% NMT and DMT in about a 2:3 ratio in the stem bark, both present in leaves20
Acacia mangium	Psychoactive39
Acacia melanoxylon	DMT, in the bark and leaf,50 but less than 0.02% total alkaloids29
Acacia mellifera	DMT, in the leaf20
Acacia nilotica	DMT, in the leaf20
Acacia nilotica subsp. adstringens	Psychoactive, DMT in the leaf
Acacia obtusifolia	Tryptamine,45 DMT, NMT, other tryptamines,51 0.4-0.5% in dried bark, 0.07% in branch tips.52
Acacia oerfota	Less than 0.1% DMT in leaf,5328 NMT
Acacia penninervis	Psychoactive30
Acacia phlebophylla	0.3% DMT in leaf, NMT20
Acacia podalyriaefolia	Tryptamine in the leaf,20 0.5% to 2% DMT in fresh bark, phenethylamine, trace amounts44
Acacia polyacantha	DMT in leaf20 and other tryptamines in leaf, bark
Acacia polyacantha ssp. campylacantha	Less than 0.2% DMT in leaf, NMT; DMT and other tryptamines in leaf, bark54
Acacia prominens	Phenylethylamine, β-methyl-phenethylamine4419
Acacia pruinocarpa	Ash used in Pituri.2139 Not known if psychoactive.
Acacia pycnantha	Ash used in Pituri,39 but less than 0.02% total alkaloids.29 Not known if psychoactive.
Acacia retinodes	DMT, NMT,55 nicotine,10 but less than 0.02% total alkaloids found29
Acacia rigidula	DMT, NMT, tryptamine, amphetamines, mescaline, nicotine and others56
Acacia roemeriana	β-methyl-phenethylamine23
Acacia salicina	Ash used in Pituri.3921 Not known if psychoactive.
Acacia sassa	Psychoactive39
Acacia schaffneri	β-methyl-phenethylamine, Phenethylamine3 Amphetamines and mescaline also found.10
Acacia schottii	β-methyl-phenethylamine23
Acacia senegal	Less than 0.1% DMT in leaf,20 NMT, other tryptamines. DMT in plant,41 DMT in bark.26
Acacia seyal	DMT, in the leaf.20 Ether extracts about 1-7% of the dried leaf mass.22
Acacia sieberiana	DMT, in the leaf20
Acacia simplex	DMT and NMT, in the leaf, stem and trunk bark, 0.81% DMT in bark, MMT5720
Acacia taxensis	β-methyl-phenethylamine23
Acacia tortilis	DMT, NMT, and other tryptamines51
Acacia vestita	Tryptamine, in the leaf and stem,20 but less than 0.02% total alkaloids29
Acacia victoriae	Tryptamines,45 5-MeO-alkyltryptamine26

List of acacia species having little or no alkaloids in the material sampled:²⁹

0% C 0.02%, C...Concentration of Alkaloids [%]

• Acacia acinacea
• Acacia baileyana
• Acacia decurrens
• Acacia dealbata
• Acacia mearnsii
• Acacia drummondii
• Acacia elata
• Acacia falcata
• Acacia leprosa
• Acacia linearis
• Acacia melanoxylon
• Acacia pycnantha
• Acacia retinodes
• Acacia saligna
• Acacia stricta
• Acacia verticillata
• Acacia vestita

Cyanogenic glycosides

Nineteen different species of Acacia in the Americas contain cyanogenic glycosides, which, if exposed to an enzyme which specifically splits glycosides, can release hydrogen cyanide (HCN) in the acacia "leaves."⁵⁸ This sometimes results in the poisoning death of livestock.

If fresh plant material spontaneously produces 200 ppm or more HCN, then it is potentially toxic. This corresponds to about 7.5 μmol HCN per gram of fresh plant material. It turns out that, if acacia "leaves" lack the specific glycoside-splitting enzyme, then they may be less toxic than otherwise, even those containing significant quantities of cyanic glycosides.²⁹

Some Acacia species containing cyanogens:

• Acacia erioloba
• Acacia cunninghamii
• Acacia obtusifolia
• Acacia sieberiana
• Acacia sieberiana var. woodii⁵⁹

Species

There are over 1,300 species of Acacia. See List of Acacia species for a more complete listing.

Famous acacia

Perhaps the most famous acacia is the Arbre du Ténéré in Niger. The reason for the tree's fame is that it used to be the most isolated tree in the world, approximately 400 km from any other tree. The tree was knocked down by a truck driver in 1973.

Identification gallery

Flowers

Acacia aneura	Acacia catechu	Acacia baileyana	Acacia berlandieri
Acacia confusa	Acacia constricta, Las Vegas, Nevada, USA	Acacia covenyi	Acacia dealbata
Acacia denticulosa	Acacia drummodii	Acacia erioloba Sossusvlei, Namibia	Acacia fimbriata Australian National Botanic Gardens, Canberra
Acacia heterophylla	Acacia longifolia	Acacia melanoxylon Nazaré, Portugal	Acacia saligna Side, Turkey
Acacia schinoides Australian National Botanic Gardens	Acacia tetragonophylla Geelong Botanic Gardens, Victoria, Australia	Acacia pennata in Talakona forest, in Chittoor District of Andhra Pradesh, India	Acacia pennata at Ananthagiri Hills, in Rangareddy district of Andhra Pradesh, India.

Bark

Acacia aneura Bark	Acacia auriculiformis Bark	Acacia berlandieri Bark	Acacia collinsii Bark
Acacia confusa Bark, Hawaii,