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Morphology & Characteristics

Distribution & Conservation

Cultivation Information

Propagation Information

Ethnobotanical Uses

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Acacia confusa

Formosan Koa Information Page

Classification - Back to Top

  • Kingdom: Plantae (Plants)

    • Subkingdom: Tracheobionta Vascular plants)

      • Superdivision: Spermatophyta (Seed Plants)

        • Division: Magnoliophyta (Flowering Plants)

          • Class: Magnoliopsida

            • Subclass: Rosidae

              • Order: Fabales

                • Family: Fabaceae

                  • Subfamily: Mimosoideae

                    • Tribe: Acacieae

                      • Genus: Acacia

                        • Species: Acacia confusa Merr.


Infraspecific Names

Varieties: Acacia confusa var. inamurai Hayata in "Icones plantarum formosanarum nec non et contributiones ad floram formosanam. 4: 4–5. 1914."

Also see: "Flora of China Editorial Committee. 2010. Fl. China 10: 1–642. Science Press & Missouri Botanical Garden Press, Beijing & St. Louis."


Species Authority:

Synonym(s): Racosperma confusum (Merr.) Pedley in "Botanical Journal of the Linnean Society 92(3): 248. 1986."

Also see: "Flora of China Editorial Committee. 2010. Fl. China 10: 1–642. Science Press & Missouri Botanical Garden Press, Beijing & St. Louis."

Common Name(s): Formosan Koa, Philippine Acacia, Taiwanese Acacia.

First Published: Philippine Journal of Science 5(1): 27–28. 1910.

Publication of Current Ranking: Philippine Journal of Science 5(1): 27–28. 1910.

Morphology & Characteristics - Back to Top

Botanical Description

An evergreen tree, the trunk up to 1 m across. Phyllodia sessile, alternate, coriaceous, lanceolate, falcate, 8-10cm long, attenuate at both ends, 3-5 parallel veined. Flowers on simple, terminal golden-yellow heads, 6-9 mm wide. Pods punctate, septate, acute ends, 5-10cm long, 8 mm across, containing 7-8 seeds. [6]

[note] We have seen seed pods containing 2-11 seeds. [7]


Key Features

Like other Acacia species, Acacia confusa has phyllodes. The bark is relatively smooth, compared to many other Acacia species. No spines will form on Acacia confusa. Flowers are in clusters as balls and bright yellow.


Growth Habit

Acacia confusa grows to be a medium-large tree forming a fairly typical umbrella crown when in the open. Trees can reach 20m+ and the trunk can obtain diameters of a little over 1m in exceptionally specimens. Stems are rarely straight, often many branched to form an even canopy above or fill in any open areas in the existing forest canopy. Note that in Taiwan Acacia confusa in the mountains, its main range, may not live to very old ages due to the extremes in rain fall, wind, earthquakes and landslides that they deal with. This is primarily the reason, as well as human destruction, that we do not often see many truly giant trees, although in climates less severe they are likely capable on monstrous sizes.

The Phyllodes (Leaf)

Acacia confusa do not have true leaves, but phyllodes. They can grow up to 11cm long and 2cm wide. They are usually slightly curved, like a scimitar, and have 3-5 parallel veins running down them. They are waxy/leathery in texture and appear alternately on the stem.

The Stem

Stems of Acacia confusa are rough, though not ridged and without spines. The bark is up to 2cm thick and often red-pink inside with yellow inner bark on younger stems. Many stems reach out from as low as ground level to make either a multi trunked tree or a solitary tree. Both growth habits are common with branching occurring at any height. Stems will obtain little more than 1m in diameter with age if they are not destroyed by natural or unnatural forces.

The Flower

Acacia confusa flowers emerge from the end of the stem (terminal) and produce roughly 6-20mm diameter balls of yellow flowers. Flowering season in Taiwan is usually summer, but it may occur sporadically year round.

The Fruit

The seed pods of Acacia confusa look like miniature flattened bean pods, not unlike the seed pods of Broom (Cytisus scoparius). Seed pods can get up to 10cm in length and contain up to 11 seeds.

The Seed

Seeds are light brown-creamy and are orthodox, meaning they can be dried and stored.

Seeds weigh an average of 0.0346g each taken from a fresh harvest of 1050 seeds which weighed 36.356g. Seeds were collected from naturally dried seeds soon after flowering on August 27, 2013. Note seeds were air dried only in front of a fan.

seed weights after being sealed in a bag with a silica gel pack was 35.527g/1050 seeds for an average of 0.0338g/seed. Note that Acacia confusa size and weights do vary considerably.

The Root

Acacia confusa roots are incredibly hard wood and very strong. They have adapted to growing through rock, and to hold themselves up in truly incredible style in rugged mountains that routinely see 1m+ a day rains and winds over 200KMH. We have seen a full grown tree, 70cm trunk diameter, growing literally 90 degrees off a cliff after having fallen during a minor land slide. It remains growing there to this day as far as we know. The roots of Acacia confusa are very beautiful yellow outer wood with a dark red inner wood from the tannins. They are very curved and sculpted, and make very beautiful ornaments and small wood crafts. The density of the root wood is incredibly hard, just as a guess it would be harder than maple.


Similar appearing species

There are numerous species of Acacia which look similar, especially based on "leaf" appearance. In Taiwan, it is distinguished by not having any spines or protrusions resembling the like, and the flowers are globular balls of yellow. They are also the only truly dominant Acacia species in Taiwan.


Distribution & Conservation - Back to Top

Native Distribution

Philippines, Taiwan(?).

Cultivated Distribution

China, Japan, Malaysia, Philippines, Taiwan, USA.

Introduced Distribution

China, Japan, Malaysia, Taiwan(?), USA.


Habitat & Climate

Acacia confusa is from SE Asia: China (Southern), Philippines (Northern), Japan (Southern) and Taiwan. It prefers semi-tropical to tropical situations. In Taiwan they grow island wide up to about 2,000m. This covers true tropical forests, seasonal monsoon type forests, rainforests and trees can withstand down to 1-2C. The southern region of Taiwan gets dry in winter, there can be as long as 6 months without rain, while in the wet season it can rain non-stop for over a month. Some mountain areas receive some of the heaviest rains on earth, especially during larger typhoons. Trees are capable of living in most these conditions, even near the ocean, however they do not seem to take well to prolonged flooding, having their roots truly submerged for long periods seems damaging to most trees we see growing in flat, low elevation areas.


Conservation

Acacia confusa is protected in the mountains of Taiwan because it is probably the most important species that helps prevent landslides and soil erosion in heavy rains and earthquakes. Outside of this, we do not know this to be protected anywhere, and in some places (Hawaii, USA) it has become an invasive species due to humans planting it.

Cultivation Information - Back to Top

Size and Habit

Acacia confusa tends to stay under 20m in Taiwan, but if left undisturbed, especially in areas of less harsh climatic conditions, it can likely reach up quite a lot taller. Acacia confusa, if grown in the open, will form a relatively even, tall-umbrella shaped canopy. It can be managed down to 2m relatively easily with pruning.


Light Preferences

Acacia confusa grows as a dominating canopy tree species in its natural range, and thus likes to have a good deal of sun. It can grow in partial shade, but will be far less bushy and lush and stretch upwards until stronger light is found. Dark cold situations are the worst.


Temperature Preferences

In Taiwan we see trees growing in areas known to reach just above freezing in the higher mountains. They take on a very different growth habit at these elevations and become shorter and wirier, compared to the large thick trunked tree with massive crowns growing in warmer, lower areas. More typically they receive cool nights in winter (down to 10-15C, average around 20C) and warm-hot days (20-30C). In summer, when it's wet, they typically get 20C+ nights and 25-38C days, though this varies greatly within Taiwan not only North to south but in elevation and any of the many amazing microclimates island wide.


Soil Preferences

In the wild it will grow in anything from hard clay silt (not ideal) to rocky/dirt or just plain rock in the mountains. In cultivation a very well drained, via use of rock grit/sand, clay. Taking 40% heavy soil (clay silt) and cutting it with 30% sharp small rock, 20% coarse sand and 10% compost should be a good start for small plants getting going.


Water & Humidity

In the wild, or cultivated in the ground, they will send out large roots for both stability and in search of permanent water. As a container plant, let slightly dry out between watering, or keep slightly moist. Acacia confusa grows throughout its range in very humid climates. They can take some of the heaviest rain imaginable, but they cannot stay flooded and without air for long periods.


Nutritional Requirements

Acacia confusa, along with many members of the Fabaceae family, have a relationship with bacteria in which their roots play host to them while they take nitrogen out of the air and eventually make it available to the plant (nitrogen fixer). The trees generally grow in poor quality soils of little nutritional value, relative to tropical/semi-tropical forests. A simple general purpose fertilizer every other month while it’s growing should suffice. Ideally nutrition should be provided via compost/mulch for plants growing in the ground. Overall they are not a very hungry species.


Reproduction

Acacia confusa flowers most profusely in summer in Taiwan, though it may flower anytime during the year, especially in warmer areas. In summer, entire mountainsides may light up in bright yellow, as the Acacia trees spend untold amounts of energy sending out thousands and thousands of flowers. Seeds are found in small bean like pods, typical of much of the family. Seeds are often eaten by insect larvae and the need for such enormous seed production is apparent. Trees will start producing flowers from about 3 years in cultivation; this is likely slightly longer in the wild, perhaps 5+.


Pruning

Prune as you see fit, they naturally grow tall and multi branched. Out in the open they will naturally take on a oval-mushroom shape in the canopy. They do not make ideal bonsai candidates due to their root sensitivity, but they do have potential. Pollarding can work well, especially in large trees, but there is a very serious risk of death of the tree. Trees that are cut to a stump in the wild seem to comeback about half the time with new growth [ 7 ].


Commercial Scale

Due to the age needed for them to build up either spice or tannins, it is not commercially grown for these intended harvests. The only commercial aspect of Acacia confusa that we are aware of in Taiwan are their sale and sue in reforestation and landslide prevention. They are commonly planted in areas where landslides are a worry. All other uses for this tree tend to use wild trees or long term plantations.

For commercial propagation, seeds are the most viable and economic method of propagation.


Pests & Disease

Acacia confusa is relatively pest free, though insect larvae do heavily attack the seeds inside the pod. Perhaps the single biggest diseases of Acacia confusa is Ganoderma species. Once the bark of an Acacia confusa tree is broken, it is open to infection. Ganoderma has proved very well adapted in Taiwan at attacking Acacia confusa specifically. Ganoderma tends not to be a huge problem for young trees, but for trees over 10cm in trunk diameter. Once planted, if small, place some shade cloth around it for a few weeks (50%) and keep slightly moist. Avoid drying out and avoid flooding. Keep above 20C and everything should work fine.


Acclimatizing New Plants

Plants should be planted right from the pot without disturbing the roots too much. Tap root breakage may not always be fatal, but they are more sensitive to root damage and subsequent infection than other tree species.


Propagation Information - Back to Top

Growing From Seed

Seeds are by far the most reliable. Cuttings are very difficult with most Acacia. Luckily, Acacia confusa produces lots of seeds and are easy to germinate. Seeds can be sown either directly into a seedling mix and kept moist, or scarification of the seeds can be utilized. Rough up the seed coat with sandpaper OR scratch it with a knife and directly sow. Soaking also works well, and is our preferred method. Place the seeds in not-quite-boiling water and let them sit for around 12 hours. When you see the seeds start to swell, sow them.

Sow seeds about 1cm deep into your seedling mix. Seedling soil should be a sandy loam that isn’t too rich and drains well. Keep moist, humid and avoid stagnating the air. Germination takes 1-10 weeks, usually very fast if soaked. Keep between 20 and 30C.


Stem, Root and/or Leaf Cuttings

To date we have rooted 1 stem via air layer using a combo of IBA and NAA hormones, most failed (or we gave up). Seed planting is the most viable and realistic route of propagation.


Grafting

We have witnessed on a few occasions Acacia confusa naturally grafting themselves together. much like approach grafting, the 2 trunks fall on each other and rub in the wind, making the bark come off causing the stem to become raw. When they sit like this, they may, over time, heal together. This effectively grafts the stems to each other. There seems no feasible reason for grafting clones of Acacia confusa at this time.


Micropropagation

We are unaware of any projects with Acacia confusa tissue culture. Due to its speedy growth and commonality, there seems little reason to develop a protocol for Acacia confusa tissue culture.


Ethnobotanical Uses - Back to Top

As a tannin source

The wood and bark are very rich in tannins. Tannins, obtained from many species including Acacia, are used to dye and stain things. Animal hides (leather) are tanned with tannins. The stem bark of Acacia confusa contains roughly 23-35% tannins [ 8 ]. A rough estimate for an average sized tree of about 30cm diameter at chest height may bring in about 10-20kg of raw dried bark suitable for tannin extraction.


As a cover for shade crops

Acacia confusa is sometimes used in mountain side farms as a shade provider for more light sensitive crops such as birds nest fern and coffee. It should be noted that Acacia confusa has no other special benefits to these species, at least we don't know of any, and they are simply used because they are the species dominating the land that is to be planted. They are also protected in Taiwan due to their incredible strength add prevention of landslides. Other tree species are also used if they happen to dominate. Acacia confusa releases some kind of chemical that makes it hard for new vegetation to germinate, thus helping reduce weeds. We are not sure if it has any negative, or positive for that matter, impact on large growing plants such as coffee transplants.


As a wood

The wood from Acacia confusa is not exported or used as a staple in the wood industry, but is used locally in Taiwan for the following uses: small wood crafts, utensils, railway ties, mining construction and decoration.


As clothing

Some of the aboriginal peoples of Taiwan would use the bark from Acacia confusa to make clothing [ 8 ].


As an oil

The flowers are said, in Taiwan, to have a fragrant oil which can be extracted.


As a charcoal source

Acacia confusa can be used to make charcoal. The high density of the wood makes it useful in such industry, though it likely isn’t utilized very much.


As a medicine

Acacia confusa is sold in Taiwanese herbal shops, although often under one of 3-5 different botanical names. The use is often blood related, but there is research also researching effects on lung and viral applications as well. Because those seem to be so far not truly well documented, we will refrain from saying too much as the studies we have read so far have not really concluded things 100% in human subjects.

One thing that appears well represented is the "spice" to be found in the bark of Acacia confusa and its very effective application of those outside of Asia in a ceremonial/spiritual/medicinal drink called Ayahuasca.


Biology & Chemistry - Back to Top

The Chemistry of Acacia confusa.

Chemical

Plant Part

Material

Quantity

Reference

Dimethyltryptamine (DMT)

Trunk Bark

Dry

0.2-1.98%

Dimethyltryptamine (DMT)

Upper Stem Bark

Dry

0.04-0.9%

Dimethyltryptamine (DMT)

Root Bark

Dry

0.3-1.9%

[ 7 ][ 9 ]

Tannins

Stem Bark

23-25%

[ 8 ]


Ecology - Back to Top


Companion Plants in Cultivation






Experimental & Notes - Back to Top


Photos - Back to Top

 Acacia confusa seeds.
 Acacia confusa tree in flower.
 Acacia confusa tree in habitat.
 Acacia confusa fallen in a storm.


References & Related Pages - Back to Top

Related Pages hosted on Kada's Garden


References

[1] Hayata. Icones plantarum formosanarum nec non et contributiones ad floram formosanam. 4: 4–5. 1914.

[2] Flora of China Editorial Committee. 2010. Fl. China 10: 1–642. Science Press & Missouri Botanical Garden Press, Beijing & St. Louis.

[3] Botanical Journal of the Linnean Society 92(3): 248. 1986.

[4] Flora of China Editorial Committee. 2010. Fl. China 10: 1–642. Science Press & Missouri Botanical Garden Press, Beijing & St. Louis.

[5] Philippine Journal of Science 5(1): 27–28. 1910.

[6] Flora of Taiwan, Second Edition. Vol. 3, Page 162. 1993.

[7] Personal Observation.

[8] Taiwan mountain crop resources and their use. [Translated from Chinese]

[9] Personal communications.


Further Reading

Ching-Yu Hsieh. 2010. Antioxidant activities and xanthine oxidase inhibitory effects of phenolic phytochemicals from Acacia confusa twigs and branches. Journal of agricultural and food chemistry 2010;58(3):1578-83.
Jyh-Horng Wu. Et Al. 2005. Phenolic antioxidants from the heartwood of Acacia confusa. Journal of agricultural and food chemistry 2005;53(15):5917-21.
Jyh-Horng Wu. Et al. 2008. Effect of phytocompounds from the heartwood of Acacia confusa on inflammatory mediator production. Journal of agricultural and food chemistry 2008;56(5):1567-73.
Jyh-Horng Wu. Et al. 2008. Online RP-HPLC-DPPH screening method for detection of radical-scavenging phytochemicals from flowers of Acacia confusa. Journal of agricultural and food chemistry 2008;56(2):328-32.
Lee JC. Et al. Anti-hepatitis C virus activity of Acacia confusa extract via suppressing cyclooxygenase-2. 2011 Jan;89(1):35-42. doi: 10.1016/j.antiviral.2010.11.003. Epub 2010 Nov 12.
Shang-Tzen Chang. Et al. 2001. Antioxidant activity of extracts from Acacia confusa bark and heartwood. Journal of agricultural and food chemistry 2001;49(7):3420-4.
Yu-Tang Tung. Et al. 2007. Antioxidant activities of natural phenolic compounds from Acacia confusa bark. Bioresource technology 2007;98(5):1120-3.
Yu-Tang Tung. Et al. 2009 A. Antioxidant activities and phytochemical characteristics of extracts from Acacia confusa bark. Bioresource technology 2009;100(1):509-14.
Yu-Tang Tung. Et al. 2009 B. Protective effect of Acacia confusa bark extract and its active compound gallic acid against carbon tetrachloride-induced chronic liver injury in rats. Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association 2009;47(6):1385-92.
Yu Tang Tung. Et al. 2010. Phytochemicals from Acacia confusa heartwood extracts reduce serum uric acid levels in oxonate-induced mice: their potential use as xanthine oxidase inhibitors. Journal of agricultural and food chemistry 2010;58(18):9936-41.
Yu-Tang Tung; Shang-Tzen Chang. 2010. Inhibition of xanthine oxidase by Acacia confusa extracts and their phytochemicals. Journal of agricultural and food chemistry 2010;58(2):781-6.
Yu-Tang Tung; Shang-Tzen Chang. 2010. Variation in antioxidant activity of extracts of Acacia confusa of different ages. Natural product communications 2010;5(1):73-6.
Yu Tang Tung. Et al. 2011. Ultrasound-assisted extraction of phenolic antioxidants from Acacia confusa flowers and buds. Journal of separation science 2011;34(7):844-51.