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31 Acacia Trees and Shrubs

Also Known as Wattles

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The acacia trees and shrubs are given the genus name of Acacia. Other species that used to be included in this genus are included in the Acacieae tribe. You may often see the name wattle used, and whistling thorn or thorntree are other common names. The majority of the species are found in Australia. There are also species found in Africa, Europe, Asia and North and South America.

They belong to the Fabaceae (legume) family. Many acacia species are able to fix nitrogen from the air. They are specifically categorized in the Mimosoideae subfamily. Examples of other family members include the eastern redbud (Cercis canadensis), yellowwood (Cladrastis kentukea), Kentucky coffee tree (Gymnocladus dioicus), weeping pagoda (Sophora japonica 'Pendula'), common gorse (Ulex europaeus), black locust (Robinia pseudoacacia), Scotch broom (Cytisus scoparius) and carob (Ceratonia siliqua)

The "leaves" on many of the species are not leaves at all. They are modified petioles, which are the parts of the stem that attach the leaves to the branch. When the petioles form in this manner, they are called phyllodes. The plant may start with real leaves and change to phyllodes while still in its early years. Other species have a modified stem called a cladode. On the species that do have true leaves, they are pinnately compound.

Most species have clusters of flowers that are yellow or cream in color. Some may be white or pink. They feature long stamens that can make it difficult to observe the small petals. The fruits are leguminous pods.

As the names whistling thorn and thorntree suggest, many species bear these sharp modified stems. Many of the Australian species do not have thorns, though.

1. Acacia Koa

Photo of the acacia koa tree
Image by Scot Nelson via Flickr used under a Creative Commons Attribution-ShareAlike license
  • Latin Name: Acacia koa
  • Other Common Names: Koa, Hawaiian mahogany
  • Native to: Hawaii
  • USDA Zones: 11
  • Height: 50'+ tall
  • Exposure: Full sun, may stand part shade

This acacia species is endemic to the Hawaiian Islands and is one of the most common trees in the state. The wood has been used to make guitars, surfboards and outrigger canoes. Another very closely related species found on the island is Acacia koaia, named koaiʻa or koaiʻe. They are quite similar and some botanists classify them as the same species.

2. Blue Leaf Wattle

Picture of the Blue Leaf Wattle
Image by Doug Beckers via Flickr used under a Creative Commons Attribution-ShareAlike license
  • Latin Name: Acacia saligna
  • Other Common Names: Port Jackson willow, orange wattle, Western Australian golden wattle, coojong, blue-leaved wattle, creeping wattle, weeping wattle, willow wattle and golden wreath wattle
  • Native to: Western Australia
  • Height: 15-30' tall
  • Exposure: Full sun

The blue leaf wattle can either be a large shrub, single-trunked tree or multi-stemmed tree. This is another species that has phyllodes instead of leaves. They have an appearance that is similar to willow leaves. The species can become invasive since the seeds are picked up by ants and birds who move them to new locations where they easily sprout.

3. Box-Leaf Wattle

Picture of the box-leaf wattle
Image by dhobern via Flickr used under a Creative Commons Attribution-ShareAlike license
  • Latin Name: Acacia buxifolia
  • Other Common Names: Box-leaved wattle, crescent acacia, hill wattle, box leaf thorn, box-leaved acacia
  • Native to: Australia
  • Height: 3-13' tall
  • Exposure: Full sun

As the species and common names suggest, the phyllodes on this shrub are similar to those of the boxwoods (Buxus spp.) This is one of the hardier species and can tolerate temperatures up to -7 Celsius (19.4 degrees Fahrenheit).

4. Coast Wattle

Picture of the coast wattle
Image by dhobern via Flickr used under a Creative Commons Attribution-ShareAlike license
  • Latin Name: Acacia longifolia
  • Other Common Names: Sydney wattle, long-leaved wattle, Sydney golden wattle, sallow wattle, golden wattle, aroma doble, acacia trinervis
  • Native to: Southeastern Australia
  • USDA Zones: Can tolerate temperatures down to the 20s in Fahrenheit
  • Height: 12-25' tall
  • Exposure: Full sun to part shade

This wattle can tolerate deer, salt and drought. It can be used to create a living fence. Green and yellow dyes can be made from the seeds and flowers, respectively. In some areas it can become invasive.

5. Espinillo

Picture of Espinillo
Image by Tehhen via Flickr used under a Creative Commons Attribution-NoDerivatives license
  • Latin Name: Acacia caven
  • Other Common Names: Espino maulino, churque, aromita, espinillo de baado, Roman cassie, caven, churqui, molina, amorito, aromo criollo and churque
  • Native to: Argentina, Bolivia, Chile, Paraguay, and Uruguay
  • USDA Zones: Tolerates some freezing temperatures down to the 10s Fahrenheit
  • Height: 8-30' tall
  • Exposure: Full sun

After a period of establishment this shrub or small tree can withstand periods of drought. The wood is used as firewood, to create charcoal or as lumber.

6. Flax-Leaf Wattle

Picture of the Flax-Leaf Wattle
Image by John Tann via Flickr used under a Creative Commons Attribution license
  • Latin Name: Acacia linifolia
  • Other Common Names: Flax-leaved wattle, white wattle
  • Native to: Eastern Australia
  • USDA Zones: 9-11
  • Height: 4-15' tall
  • Exposure: Full sun to part shade

This acacia shrub has phyllodes that are similar to flax leaves. The flowers are cream or light yellow in color and may appear in both summer (which is December to March in the Southern Hemisphere) and winter (June to September). In some areas it can take over and become invasive.

7. Green Wattle

Picture of the green wattle
Image by brewbooks via Flickr used under a Creative Commons Attribution-ShareAlike license
  • Latin Name: Acacia decurrens
  • Other Common Names: Sydney wattle, wattah, Queen wattle, black wattle, golden teak, early black wattle, wattle bark, tan wattle, Brazilian teak, golden wattle, acacia bark
  • Native to: New South Wales, Australia
  • USDA Zones: 9-11
  • Height: 10-40' tall
  • Exposure: Full sun

Gum from this tree can be eaten and is used in jellies. The flowers are also edible. The bark can be used for tanning. In South Africa it is considered to be invasive and nicknamed "green cancer".

8. Hedgehog Wattle

Picture of the hedgehog wattle
Image by John Tann via Flickr used under a Creative Commons Attribution license
  • Latin Name: Acacia echinula
  • Other Common Names: Hooked wattle
  • Native to: Australia
  • Height: 1-10' tall

The common name is inspired by the fact that this species has phyllodes that are very prickly like a hedgehog.

9. Hickory Wattle

Picture of the hickory wattle
Image by dhobern via Flickr used under a Creative Commons Attribution license
  • Latin Name: Acacia penninervis
  • Other Common Names: Mountain hickory, blackwood
  • Native to: New Zealand and Australia
  • USDA Zones: 9-10
  • Height: 7-33' tall
  • Exposure: Full sun to light shade

The hickory wattle features round creamy flowers that are formed in clusters called racemes.

10. Juniper Wattle

Picture of the juniper wattle
Image by lookscloser via Flickr used under a Creative Commons Attribution-ShareAlike license
  • Latin Name: Acacia ulicifolia
  • Other Common Names: Prickly Moses
  • Native to: Australia
  • Height: 1-13' tall
  • Exposure: Full sun to light shade

You can use this thorny species as a privacy hedge. The species name of ulcifolia suggests that the phyllodes on this shrub are similar to the leaves of gorse(Ulex). Previously it was known as Acacia juniperina. The flowers can be either cream or white. This shrub can tolerate some frost as low as -7 Celsius (19.4 Fahrenheit).

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