What Is The Hardest Wood In The World? Australian Buloke (Janka Scale)

Man looking at various types of wood planks wonders, what is the hardest wood in the world according to the janka wood scale and considering the wood hardness scale, what is Australian buloke wood hardness rating?

There is something of a debate when it comes to answering the question, what is the hardest wood in the world?

Most experts are of the opinion that the Australian Buloke, which is an ironwood tree, provides the hardest wood in the world, with a Janka hardness rating of 5,060 lbf.11 Others argue that Quebracho (which translates to ‘ax-breaker’ in Spanish) is the tree with the hardest wood in the world.

But what does ‘hardness’ related to wood actually refer to? While it’s easy to assume that hardness refers to strength, that is not entirely the truth.

The hardness makes up one measurement, of the many that exist, which establishes how much force it takes to destroy any given wood piece.

In the case of hardness measurement, hardness equals resistance to indentation. This, in simple terms means, hardness is measured by how much force is required to make a sizable mark in the wood.

So, what is the hardest wood in the world? The Janka test says Australian Buloke.

Related Reading: How Many Trees Are in the World?

What Is the Hardest Wood in the World? (Wood Hardness Scale)

For the purpose of measuring hardness, the Janka test and Janka wood hardness scale are used.

The test was created by Gabriel Janka and basically consists of a 0.44-inch steel ball with a small ‘belt’ placed around it. The ball is pressed into a piece of wood until it has made a dent up to the little belt (which is halfway).

The score from this Janka test is the amount of force required to get the ball into the wood.16

However, there are several factors that come into play to ensure the test is done properly. These include:

  • A piece of wood containing exactly 12% moisture
  • The wood thickness must be exactly 2 inches, as must be the width, while the length must be 6 inches
  • When the test is done, the ball should be pressed into each side of the piece of wood, to ensure six scores at the end, then the average is taken from these scores
  • The wood itself must be derived from the main tree trunk, as opposed to a branch
  • There should be no knots in the wood
  • The ball must be pressed into the wood at an average of 0.25 inches a minute1

These conditions are required for the Janka test, so that all types of wood are treated exactly the same.

What Is the Hardest Wood in the World? (Janka Wood Scale)

The Janka Wood Scale offers the pounds-force rating of different wood species including domestic and exotic wood.

The below Janka wood scale chart indicates the hardness of both domestic and exotic wood species, with high ratings meaning a higher level of hardness than low ratings.18 (The rating is given in pounds-force (lbf).5,7

The following list starts with some of the hardest woods that have been tested, and proceeds to the softest.

Wood SpeciesJanka Hardness Rating (in pounds-force)
Lignum Vitae4380 lbf
Snakewood253800 lbf
Red Coolibah Burl3730 lbf
Argentine Lignum Vitae (Image: Abarmot26)3710 lbf
Brazilian Ebony3692 lbf
African Blackwood3670 lbf
Figured Katalox3660 lbf
Katalox (Image: Abarmot26)3660 lbf
Brown Ebony3590 lbf
Mopani3390 lbf

Argentine Lignum Vitae


Wood SpeciesJanka Hardness Rating (in pounds-force)
Grey Box Burl3370 lbf
Camatillo3340 lbf
Kingwood3340 lbf
Cumaru3330 lbf
Pink Ivory3230 lbf
Macassar Ebony (Image: B. Ratunde26)3220 lbf
Pau Santo3200 lbf
Angelim Pedra3160 lbf
Royal Ebony3080 lbf
Gaboon Ebony (Image: Disputantum26)3080 lbf

Macassar Ebony

Gaboon Ebony

Wood SpeciesJanka Hardness Rating (in pounds-force)
Mun Ebony3000 lbf
Cocobolo2960 lbf
Yellow Box Burl (Image: Ottre27)2920 lbf
Bloodwood2900 lbf
Osage Orange2760 lbf
Madagascar Rosewood2720 lbf
Granadillo2700 lbf
Olivewood (Image: Androstachys26)2690 lbf
Jatoba2690 lbf
Amazon Rosewood2620 lbf

Yellow Box Burl


Wood SpeciesJanka Hardness Rating (in pounds-force)
Marblewood2532 lbf
Figured Purpleheart2520 lbf
Purpleheart (Image: Villanueva27)192520 lbf
Tulipwood (Image: Rob Hille27)2500 lbf
Brown Mallee Burl2490 lbf
Tamboti2480 lbf
East Indian Rosewood2440 lbf
Indian Ebony2430 lbf
Cochen Rosewood2430 lbf
Quilted Bubinga2410 lbf


Tulipwood Trunk

Wood SpeciesJanka Hardness Rating (in pounds-force)
Bubinga (Image: Rotational27)2410 lbf
Figured Bubinga2410 lbf
Santos Mahogany2400 lbf
Argentine Osage Orange2400 lbf
Spalted Tamarind (Image: Bishnu28)2318 lbf
Chakte Viga2250 lbf
Honduras Rosewood Burl2200 lbf
Honduras Rosewood2200 lbf
Chechen2200 lbf
Goncalo Alves2160 lbf


Spalted Tamarind

Wood SpeciesJanka Hardness Rating (in pounds-force)
Leopardwood2150 lbf
Sucupira2140 lbf
Black Palm (Image: DEZALB28)122020 lbf
Bocote2010 lbf
Ziricote1970 lbf
Padauk1970 lbf
Bolivian Rosewood1960 lbf
Wenge1930 lbf
Red Palm1900 lbf
Yellowheart1978 lbf

Black Palm


Wood SpeciesJanka Hardness Rating (in pounds-force)
Jarrah Burl1860 lbf
Zebrawood (Image: Mnemosine27)1830 lbf
Figured Zebrawood1830 lbf
Hickory (Image: Internet Archive Book Images | NCSU Libraries29)1820 lbf
Afzelia Burl1810 lbf
Figured Camphor Bush1800 lbf
Camphor Bush Burl1800 lbf
Black & White Ebony1780 lbf
Merbau1712 lbf
Afrormosia1560 lbf



Wood SpeciesJanka Hardness Rating (in pounds-force)
Honey Locust (Image: Josie Weiss33)1548 lbf
Canarywood1520 lbf
Sapele1500 lbf
Madrone Burl (Image: Internet Archive Book Images | NCSU Libraries29)1460 lbf
Rift Sawn Hard Maple1450 lbf
Spalted Maple1450 lbf
Hard Maple Burl1450 lbf
Bark Pocket Maple1450 lbf
Quarter Sawn Maple1450 lbf
Curly Hard Maple1450 lbf

Honey Locust

Madrone Burl

Wood SpeciesJanka Hardness Rating (in pounds-force)
Hard Maple141450 lbf
Birdseye Maple1450 lbf
Quilted Sapele1439 lbf
Eucalyptus (Image: Kylie128)1400 lbf
Mayan Walnut (Image: Internet Archive Book Images | NCSU Libraries29)1400 lbf
English Brown Oak1360 lbf
Ebiara1350 lbf
White Oak1335 lbf
Quarter Sawn White Oak1335 lbf
Shedua1330 lbf


Mayan Walnut

Wood SpeciesJanka Hardness Rating (in pounds-force)
Swamp Ash (Image: Minnecologies32)1320 lbf
Curly White Ash1320 lbf
White Ash1320 lbf
Makore1294 lbf
Figured Makore1294 lbf
Narra1260 lbf
Birch Burl1260 lbf
Flame Birch1260 lbf
Curly Narra1260 lbf
Birch (Image: Petra (Pezibear)28)1260 lbf

Swamp Ash


Wood SpeciesJanka Hardness Rating (in pounds-force)
Amboyna Burl1260 lbf
Spalted Oak1220 lbf
Quarter Sawn Red Oak1220 lbf
Curly Oak1220 lbf
Red Oak (Image: Internet Archive Book Images | NCSU Libraries29)211220 lbf
Nicaraguan Rosewood1210 lbf
Mirindiba1200 lbf
Masur Birch1200 lbf
Redheart1200 lbf
Acacia (Image: Herbert II Timtim (herbert11timtim)28)1180 lbf

Spanish Cedar


Wood SpeciesJanka Hardness Rating (in pounds-force)
Koa (Image: Scot Nelson29)1170 lbf
Thuya Burl1160 lbf
Figured Mango1100 lbf
African Mahogany1100 lbf
Teak1080 lbf
Curly Pyinma1055 lbf
Holly1020 lbf
Figured Walnut1010 lbf
Walnut1010 lbf
Peruvian Walnut960 lbf


Thuya Burl

Wood SpeciesJanka Hardness Rating (in pounds-force)
Ambrosia Maple950 lbf
Curly Cherry950 lbf
Soft Maple950 lbf
Cherry Burl950 lbf
Curly Soft Maple950 lbf
Tornillo950 lbf
Cherry950 lbf
Anigre930 lbf
Lacewood891 lbf
Spalted Hackberry880 lbf

Ambrosia Maple


Wood SpeciesJanka Hardness Rating (in pounds-force)
Western Maple (Image: Internet Archive Book Images | NCSU Libraries30)850 lbf
Black Ash17850 lbf
Curly Western Maple850 lbf
Western Maple Burl850 lbf
Quilted Western Maple850 lbf
Genuine Mahogany (Image: jessicuak28)800 lbf
Spanish Cedar600 lbf
Mappa Burl540 lbf

Western Maple

Genuine Mahogany

Wood SpeciesJanka Hardness Rating (in pounds-force)
Poplar540 lbf
American Chestnut540 lbf
Butternut490 lbf
Guanacaste (Image: Alison Phillips32)470 lbf
Basswood Tree410 lbf
Aspen380 lbf
Buckeye Burl (Image: internet Archive Book Images | NCSU Libraries30)350 lbf2


Buckeye Burl

Hardest Wood in the World

The below wood species are some of the hardest woods in the world:

Australian Buloke: 5,060 lbf

Australian Buloke is often reported as producing the hardest wood in the world, even though it must be considered that this ranking is based on only one data source.

Schinopsis Brasiliensis: 4,800 Ibf

Schinopsis Brasiliensis belongs to the cashew family and is also known as Baraúna. This tree is harvested mainly for construction because its wood is so hard. Excessive harvesting has led to the tree becoming an endangered species.

Schinopsis Balansae: 4,570 Ibf

This hardwood tree is also well known as Argentina’s National Forest Tree after it was declared so in 1956.

It is also called the willow leaf red quebracho and its wood is mainly used for quebracho extract which consists of around sixty-three percent pure tannin.

Lignum Vitae (Tree of Life): 4,500 Ibf

Lignum Vitae is also known as the tree of life and is one of the hardest and heaviest woods on the planet.15 This tree is currently listed as endangered because of the over-extraction of resin.

Piptadenia Macrocarpa: 3,840 Ibf

This timber tree is often compared to a mimosa tree and is native to several South American countries.

The wood from this tree is very durable and hard and is often used for construction and marine purposes.

Snakewood: 3,800 Ibf

Snakewood wood is considered to be one of the heaviest commercial woods worldwide, as well as one of the hardest. It is popular for use in the manufacturing of violins and tools.

Brazilian Olivewood: 3,700 Ibf

Brazilian Olivewood has a deceptively delicate appearance, as it is very hard and durable. It is commonly used for interior decoration and upmarket furniture.

Brazilian Ebony: 3,692 Ibf

Like its counterpart, olivewood, Brazilian ebony wood is also heavy and hard. It is almost black in color with a grain that runs in straight lines.

Ebony wood in general is popular for use in instruments and furniture.

Brazilian Walnut: 3,684 Ibf

Brazilian walnut wood is known for being exceptionally durable and pest resistant. An example of this is the beach boardwalk in Coney Island, which was built using Brazilian walnut wood.

This boardwalk lasted for 25 years before replacements were required. However, this type of wood is tough to work with, because it is very dense and hard. It is a popular wood for flooring purposes.

African Pearwood: 3,680 Ibf

African pearwood wood is highly durable and easy to work with. It is commonly used for furniture and veneer purposes.

This tree is also listed as vulnerable because of ongoing exploitation.

Furthermore, the below table indicates some more details about the hardest hardwoods in the world:

Hardwood SpeciesScientific NameJanka Hardness Rating (in pounds-force)
Cebil (Curupay)Anadenanthera colubrina3630 lbf
Katalox / WamaraSwartzia spp.3655 lbf
Black Ironwood20Krugiodendron ferreum3660 lbf
African BlackwoodDalbergia melanoxylon3670 lbf
Camelthorn (Image: Sohadiszno31)Vachellia erioloba3680 lbf
VerawoodBulnesia arborea3710 lbf
SnakewoodBrosimum guianensis3800 lbf
GidgeeAcacia cambagei4270 lbf
Lignum VitaeGuaiacum officinale4390 lbf
QuebrachoSchinopsis spp.4570 lbf3



Related Reading: How Many Trees Are Planted Each Year?

The below table indicates the comparison of wood hardness when choosing wood for flooring purposes:

Very Hard WoodHard WoodModerately Hard WoodSoft Wood
Spotted GumBrushboxMessmateRadiata Pine
Red IronbarkTallowwoodMountain AshAraucaria
Gray IronbarkStringybarkTasmanian OakKauri
BlackbuttRiver Red GumVictorian AshWhite Baltic
New England BlackbuttRose GumShining GumWestern Yellow Pine
Forest Red GumSydney Blue GumManna GumRimu
TurpentineSouthern Blue GumMyrtleTeak4
White MahoganyJarrahBlackwood
Gympie MessmateKarriCypress
Gray BoxMarriAmerican White Oak
WandooKwilaEuropean Oak
Brazilian CherryNorthern BoxEuropean Ash
JatobaKempasMaple Sugar

The option that comes in as the average choice around the world when choosing hardwood for flooring, is red oak wood.

The other options include the following:

Chart that shows the hardwood flooring average choice per janka hardness rating.

When it comes to ‘good’ Janka ratings, a ranking of 1,000 lbs or more is considered to be acceptable. But it must also be considered that even though a certain type of wood may have a very high Janka score, it is not a guarantee that the wood won’t warp or wear.

Speaking of warping and wearing, and denting, the below wood is rated as the softest wood on the Janka wood hardness scale:

WoodScientific NameJanka Hardness RatingCommon Uses
Western Red CedarThuja plicata350 lbfWestern Red Cedar is commonly used for musical instruments such as guitars, but because it is so soft, it is not easy to keep it from denting during construction.
Black Cottonwood (Image: Patrick Alexander30) and Quaking AspenPopulus tremuloides / P. trichocarpa350 lbfThese two types of wood have similar Janka scores and are both soft and easily dented or damaged. Black cottonwood is used for paper while quaking aspen is used for lumber.
Atlantic White CedarChamaecyparis thyoides350 lbfWhile Atlantic white cedar wood is soft, it has excellent resistance against decay and moisture. It is often used for shingles and in boat construction.
Yellow Buckeye (Image: Internet Archive Book Images | NCSU Libraries30)Aesculus octandra350 lbfThis softwood is popular for use in guitar manufacturing and other high-end wood products. It is also used for lumber.
Subalpine FirAbies lasiocarpa350 lbfSubalpine fir wood is the softest of all fir woods, except for European silver fir. This soft wood is used for pulp, veneer, and lumber.
WoodScientific NameJanka Hardness RatingCommon Uses
Northern White Cedar23Thuja occidentalis350 lbfNorthern white cedar wood is considered one of the softest cedars and is used for various products including pails, poles, fencing, logs, and more.
European Silver FirAbies alba320 lbfThis is the softest wood of all fir woods and makes for lightweight timber that can be used for pulp, plywood, and lightweight furniture.
Balsam PoplarPopulus balsamifera300 lbfBeing one of the lightest woods, balsam poplar wood is commonly used for crates, veneer, and pulp.
PaulowniaPaulownia spp.260 lbfPaulownia is a type of softwood that truly stands on its own merit. Even though it is a very soft and light wood, it is also strong and fire, water, and pest-resistant.

Paulownia wood can be used for making instruments, in construction, and for plywood.

BalsaOchroma pyramidale90 lbfBalsa is officially both the lightest and the softest wood on the wood market today. It is often used for insulation and recreational purposes such as model vehicles and planes.

Black Cottonwood

Yellow Buckeye

When looking at all of the wood ratings, it must also be considered that while the Janka scale is still the go-to scale for wood hardness measuring worldwide, it might no longer be relevant to some industries, including the wood flooring industry.6

For this reason, many flooring companies and associates prefer to use the new table as indicated above, which groups wood into Very Hard, Hard, Moderate Hard, and Soft categories.

The reasons debated for the Janka scale being outdated for the flooring industry are as follows:

  • Wood is used in a different way when it comes to flooring. For instance, most modern floors require more than one type of material, which means the Janka rating no longer applies.
  • Studies into tree regrowth have shown that the Janka scale’s information may be too out of date for some industries to use. This is because the existing scores are based on primeval wood data.
  • The Janka score also doesn’t provide the complete picture when it comes to ranking the hardness of a particular wood. For instance, while it is good to know the hardness of the wood related to dent resistance, it is essential to measure the stability and lifespan of the wood, as well as the wood’s ability to recover after being damaged.6

Strongest Types of Wood

The strongest types of wood include the following factors that influence its strength:

  • Increased microfibril angle may cause lesser elasticity.
  • Extractives from heartwood may add several substances that make wood stronger.
  • In addition to these substances, heartwood extractives are also known to add other substances that would increase the density of the wood without making a noticeable difference in the strength.
  • Some types of wood always have defects that will affect its overall strength.7

World’s Strongest Wood

The world’s strongest wood is ranked in order of how popular the wood is for building and construction applications:

  1. Australian Buloke
  2. Schinopsis Brasiliensis
  3. Brazilian Ebony
  4. Schinopsis Balansae13
  5. Lignum Vitae8

The Strongest Tree in the World

Looking at the above information, it might be surprising to learn that the strongest tree in the world is considered to be the Giant Sequoia.

A giant sequoia named General Sherman has a height of 274.9 feet and a girth of 79 feet.

This makes it the biggest tree in the world.

What Is the Hardest Wood in the World? Most Durable Wood

The giant sequoia redwood is known for having some of the most durable wood in the world. Wood from this tree is often used for outdoor furniture and decking because of its exceptional weather resistance.

Sequoia is also the most expensive wood in the world when calculated by cubic meters.

Other woods that deserve the distinction of most durable wood is:

  • Black Cherry Wood
  • White Oak Wood
  • Cypress Wood
  • Red Mulberry Wood
  • Black Locust Wood
  • Southern Yellow Pine Wood
  • Black Walnut Wood
  • Eastern Red Cedar Wood9

What Is the Hardest Wood in the World?

When compiling a comprehensive answer to the question, what is the hardest wood in the world, it is important to list the hardest wood to split.

Hardest Wood To Split

The hardest wood to split includes the following:

What Is the Hardest Wood in the World?

Also, when it comes to answering the question, of what is the hardest wood in the word, the wood hardness for woodworking must also be considered.

Woodworking Wood Hardness Chart

When looking at a woodworking wood hardness chart, the most important information is the pressure to mar (in pounds), which indicates the hardness of the face of the wood (excluding the sides and edges).

The below chart is useful when deciding what wood to use for a project:

Species of WoodPressure to Mar (in pounds)
Hickory and Pecan1,820
Hard Maple (Image: Ultramarinfoto31)1,450
White Oak1,360
Red Oak1,290
Yellow Birch (Image: NNehring31)1,260
Green Ash1,200
Black Walnut1,010
Soft Maple950

Hard Maple

Yellow Birch

Species of WoodPressure To Mar (in pounds)
Elm (Image: daizuoxin31)830
Yellow Poplar540



It is clear that the different types of wood that are ranked as the hardest woods in the world, all have their own characteristics to consider.

What Does Janka Hardness Refer To?

Janka hardness refers to the Janka hardness test developed by researcher Gabriel Janka. The Janka test measures the force used to dig a 0.44 steel ball into a piece of wood.

Janka hardness tests are often required to determine the suitability of wood for flooring.

Is the Australian Buloke the Hardest Wood Around the World?

Australian Buloke wood is the hardest commercially available wood in the world.

The Australian Buloke Tree grows to heights of 66 feet and its life span is around 15 years.

Chart that shows the woodworking hardness per species of wood.

As the name suggests, the tree is native to Australia.

What Is the Carbon Footprint of Timber?

Timber is wood that has been specially prepared for furniture manufacturing and construction. Timber also has a carbon footprint which is explained as: Every dry ton of timber captures around 1.8 tons of CO2 from the atmosphere.

The CO2 remains locked in the wood which assists in offsetting harmful emissions. It is estimated that building timber cities could cut around 100 billion tons of carbon dioxide from the atmosphere by 2100.

However, the transportation of timber does release GHG emissions because of vehicle fossil fuels.

How Much Weight Can Plywood Hold?

The weight-bearing capacity of plywood is dependent on the thickness of the plywood, in other words, the thicker the sheet of plywood, the stronger the sheet of plywood.

For instance, a 12-inch by 36-inch sheet of plywood that is 1/4 inch thick will support only 5 pounds. However, a 12-inch by 36-inch sheet of plywood that is 3/4 inches thick will support up to 50 pounds.

Knowing the answer to the question, what is the hardest wood in the world, might come in handy one day, but at the very least, it’s very cool to understand how trees are ranked by their Janka score and what that means.

Frequently Asked Questions About What Is the Hardest Wood in the World

What Is the Hardest Wood in the World?

The hardest wood in the world is considered by many experts to be the Australian Buloke. This wood has a Janka hardness rating of 5,060 lbf and is native to the Australian continent.

What Is the Strongest Wood?

The strongest wood is listed as follows (for building purposes):

  • Oak tree wood
  • Ash tree wood
  • Hickory tree wood
  • Ebony tree wood
  • Cherry tree wood
  • Lignus Vitae wood
  • Schinopsis balansae wood
  • Brazilian ebony wood
  • Schinopsis brasiliensis wood
  • Australian buloke wood

What Is the Hardest Wood?

The hardest wood in the world includes the following:

  • Quebracho Wood: 4,570 lbf
  • Lignum Vitae Wood: 4,390 lbf
  • Gidgee Wood: 4,270 lbf
  • Snakewood Wood: 3,800 lbf
  • Australian Buloke Wood: 3,370 lbf
  • Verawood Wood: 3,710 lbf
  • Camelthorn Wood: 3,680 lbf
  • African Blackwood Wood: 3,680 lbf
  • Gray Ironbark Wood: 3,680 lbf
  • Black Ironwood Wood: 3,660 lbf
  • Curupay Wood: 3,360 lbf
  • Ipe Wood: 3,510 lbf
  • Cumaru Wood: 3,330 lbf
  • Desert Ironwood Wood: 3,260 lbf
  • Bulletwood Wood: 3,130 lbf

What Are the Grades of Marine Plywood?

Marine plywood is the strongest type of plywood and comes in the following grades:

  • A-A
  • A-B
  • B-B
  • Medium Density Overlay
  • High-Density Overlay

Is It Possible To Get Free Tree Removal in Exchange for Wood?

It is possible to get free tree removal in exchange for wood, by considering the following:

  • How hard is it to reach the location of the tree? If the tree is in a difficult-to-reach location, a tree removal company may not want to remove it free of charge.
  • What is the tree species? If the tree is a valuable species, a tree removal company may be convinced to remove it for free in exchange for the wood.
  • How big is the tree? Bigger trees take longer to remove, and the tree removal company may want to evaluate whether it is worth their time to remove them.
  • Will the local utility company remove the tree for free or for wood?
  • Will home insurance cover the cost of a potential accident during tree removal?


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2Bell Forest Products. (2022.). Janka Hardness chart for Exotic Wood and Domestic Wood. Bell Forest Products. Retrieved December 21, 2022, from <https://www.bellforestproducts.com/info/janka-hardness/>

3Meier, E., & Bootle, K. R. (2022). Top Ten Hardest Woods. The Wood Database. Retrieved December 21, 2022, from <https://www.wood-database.com/top-ten-hardest-woods/>

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5Superior Hardwood Flooring. (2022). Janka Hardness Scale – Superior Flooring. Superior Hardwood Flooring. Retrieved December 21, 2022, from <https://www.superiorflooring.ca/janka-hardness-scale/>

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8Dane, K. (2021, September 24). Ranking The 10 Strongest Woods to Build With. Inspired Homes. Retrieved December 21, 2022, from <https://inspiredhomes.uk.com/ranking-the-10-strongest-woods-to-build-with/>

9Saxton, T. (2021, May 28). Your Guide to the Most Durable Wood Species for Outdoor Use. Rise. Retrieved December 21, 2022, from <https://www.buildwithrise.com/stories/durable-outdoor-wood-guide>

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11Australian Government’s National Environmental Science Program. (2022). Restoring Buloke Woodland Structure. Threatened Species Recovery Hub. Retrieved December 22, 2022, from <https://www.nespthreatenedspecies.edu.au/media/vwrbhuno/1-2-2-restoring-buloke-woodland-structure-guide-factsheet_v9.pdf>

12Doubrava, N., Blake, J. H., Munnerlyn, C., & Williamson, J. (2021, September 10). PALM DISEASES & NUTRITIONAL PROBLEMS. Clemson Cooperative Extension Home and Garden Information Center. Retrieved December 23, 2022, from <https://hgic.clemson.edu/factsheet/palm-diseases-nutritional-problems/>

13Emanuele, E., Šket, P., Causin, V., Zanetti, M., & Tondi, G. (2021, December 16). Development of Quebracho (Schinopsis balansae) Tannin-Based Thermoset Resins. National Library of Medicine. Retrieved December 23, 2022, from <https://www.ncbi.nlm.nih.gov/pmc/articles/PMC8706668/>

14Godman, R. M., Yawney, H. W., & Tubbs, C. H. (2022). Sugar Maple. USDA Forest Service. Retrieved December 23, 2022, from <https://www.srs.fs.usda.gov/pubs/misc/ag_654/volume_2/acer/saccharum.htm>

15Government of The Bahamas. (2022). The Lignum Vitae – National Tree of The Bahamas. The Government of The Bahamas. Retrieved December 23, 2022, from <https://www.bahamas.gov.bs/wps/portal/public/about%20the%20bahamas/national%20symbols/the%20lignum%20vitae%20-%20national%20tree%20of%20the%20bahamas/!ut/p/b1/vZLJkqJAGISfxQegKaDYjigIFBQgiwoXQ0CQTUBwgacfey6zREz3HKan_lNFfFkZmfWTEbkno8vxXuTHsWgvx_r9HnEHBqhYkqCAVRZwQA8cU3J4jbYp9gWEHwAQ_J0e_OFIn-p35N4PWFNucb42H4bKJsqxKeTpycoWES5lLnCxowPuRJlxasCmu2A0YRWnZ8UQ6CKmfZxdN6ziRX1kFBAdJxw1ru_0vdExTh06yObR8MCKrYAhV9aasTpHW8bSqu4OldpXG4eXcmWSS_5Mn-XIqjMENuKYGIpcDeMlaVV0aOPJHA8ECnkKhddEZ5lrZyV9eiyoMWwBbNq9IDj9Q5vxY7F4ZYo-jG3QnwDvtX8HPujV0trmRIYvjP_pHX8LgE4ByfWoDRAsivTJPYAHr5w6fa5mt5xdbMlLC4NhBhWFxqDcWUGNvVSlfFMBQA6eOOjsMV7qfonQMPpOunWDpSRRz_r0_N3Qpn3xZbiiOCNggQfgVxuqrC28muJ9R2JpoNrU_zZk_mulqmODL0_4y9LAzb__Q0RGRdy8PZLmDbwJIkexvABFgQMQCjy5rQPhGef4KTs3Yw0J5GjZlclPcLe5sm07WDsUnTmC8xgxtYppqdeXTYFcJVi5kGjpThwEjovTO21kS0K5xrfZrAFH937LbLWt5ZroNDRG0K3hXqqjx_auJXdBjE-MmVPDeRP7nh1WHFvC0_VyUVXXFTisq2j9zFZ96226BkxCgpw0y9mnHe3UGVXBZDPYP3p4wqMYP9QxtfJedJu-9NGuaaTkph9PXVg5t8Qo2iTKDNNeZWGLDqV0Ie6zNhN3jZB36tYWqgXZNUFw75RM3s8_RlosvgHYDn1d/dl4/d5/L2dBISEvZ0FBIS9nQSEh/>

16Green, D. W., Begel, M., & Nelson, W. (2006). Janka Hardness Using Nonstandard Specimens. Forest Service US Department of Agriculture. Retrieved December 23, 2022, from <https://www.fs.usda.gov/research/treesearch/23824>

17Gucker, C. L. (2005). Fire Effects Information System (FEIS). US Forest Service. Retrieved December 23, 2022, from <https://www.fs.usda.gov/database/feis/plants/tree/franig/all.html>

18Kasseney, B. D., Deng, T., & Mo, J. (2011, June). Effect of Wood Hardness and Secondary Compounds on Feeding Preference of Odontotermes formosanus (Isoptera: Termitidae). PubMed.Gov. Retrieved December 23, 2022, from <https://pubmed.ncbi.nlm.nih.gov/21735905/>

19Mahr, S. (2022). Purple Heart, Tradescantia pallida. Wisconsin Horticulture Division of Extension. Retrieved December 23, 2022, from <https://hort.extension.wisc.edu/articles/purple-heart-tradescantia-pallida/>

20Mayer, W. (2022, September 9). Intro to Trees of Indiana: Ironwood. Purdue University. Retrieved December 23, 2022, from <https://ag.purdue.edu/news/department/forestry-and-natural-resources/2022/09/intro-to-trees-of-indiana-ironwood.html>

21NC State University. (2022). Quercus rubra. NC State Extension. Retrieved December 23, 2022, from <https://plants.ces.ncsu.edu/plants/quercus-rubra/>

22Science.Gov Alliance. (2022). Sample records for eastern cottonwood trees. Science.Gov. Retrieved December 23, 2022, from <https://www.science.gov/topicpages/e/eastern+cottonwood+trees>

23USDA, NRCS, & National Plant Data Center & the Biota of North America Program. (2022). NORTHERN WHITECEDAR. US Department of Agriculture. Retrieved December 23, 2022, from <https://plants.usda.gov/DocumentLibrary/plantguide/pdf/pg_thoc2.pdf>

24US Department of Interior. (2022). Eucalyptus Trees. National Park Service. Retrieved December 23, 2022, from <https://www.nps.gov/places/eucalyptus-trees.htm>

25US Fish and Wildlife Service. (2022). Snakewood. US Fish and Wildlife Service. Retrieved December 23, 2022, from <https://www.fws.gov/species/snakewood-rauvolfia-serpentina>

26Argentine Lignum Vitae by Abarmot, Katalox by Abarmot, Macassar Ebony by B. Ratunde, Gaboon Ebony by Disputantum, and Olivewood by Androstachys, retrieved from <https://commons.wikimedia.org/wiki/Main_Page>

27Yellow Box Burl by Ottre, Purpleheart by Villanueva, Tulipwood Trunk by Rob Hille, Bubinga by Rotational, Zebrawood by Mnemosine <https://commons.wikimedia.org/wiki/Main_Page>

28Spalted Tamarind by Bishnu Sarangi (sarangib), Black Palm by DEZALB, Eucalyptus by kylie1, Birch by Petra (Pezibear), Acacia by Herbert II Timtim (herbert11timtim), and Genuine Mahogany by jessicuak <https://pixabay.com>

29Koa by Scot Nelson, Hickory by Internet Archive Book Images | NCSU Libraries, Madrone Burl by Internet Archive Book Images | NCSU Libraries, Mayan Walnut by Internet Archive Book Images | NCSU Libraries, Red Oak by Internet Archive Book Images | NCSU Libraries, retrieved from <https://www.flickr.com/>

30Western Maple by Internet Archive Book Images | NCSU Libraries, Yellow Buckeye by Internet Archive Book Images | NCSU Libraries, Buckeye Burl by Internet Archive Book Images | NCSU Libraries, and Black Cottonwood by Patrick Alexander, retrieved from <https://www.flickr.com/>

31Camelthorn by Sohadiszno, Hard Maple Wood Texture by Ultramarinfoto, Elm by daizuoxin, Aspenwood by Ninjuna, and Yellow Birch NNehring, <https://www.canva.com/>

32Guanacaste by Alison Phillips and Swamp Ash by Minnecologies, retrieved from <https://commons.wikimedia.org/wiki/Main_Page>

33Photo by Josie Weiss via <https://unsplash.com/photos/P86I5vNtRv4?utm_source=unsplash&utm_medium=referral&utm_content=creditCopyText>