November 2013 – florabank.com.au

The Evolution of Flora in Australia

The evolution of Australia’s flora begins with the continental drift that divided all the continents of the world into separate land masses. As an isolated island, its flora flourished undisturbed for centuries. A flood that covered the entire continent acted to divide it and created four separate islands, which helped gave some of the soil in Australia its alkaline base.

Evidence that the flood occurred, covering the landmass with a seabed and marine life, is seen in the Outback. Fossilized sea organisms and mollusks have been found in this part of the country and the soil there is acidic. During this time, the flora of each separate island developed and flourished, with each area developing its own unique catalog of plants.

After the flooding ended, there was a demarcation between all of the islands due to limestone embedded in the soil. Since there was a difference in the soils between all of the islands, the flora that existed in each area could not migrate to another island. They could not survive the differences in soil. Also, once the waters subsided, evolution sped up and new plants began to grow in areas where new land was available.

Migrating Flora

The Ice Ages had little effort on plant life in Australia because it was warmer there than most other areas of the world. While some parts of the world had ice in excess of 3000 meters thick, the Australian continent had a fairly shallow ice coverage of 10 meters. However, a wide-spread drought that took place around 5,000 years ago and lasted for several centuries. The effects of it caused several extinctions among the country’s flora and soils also migrated during this period.

There were areas of the landmass that were mostly unaffected during this time and retained more moisture than other parts of the large island. These areas included:

Mount Buffalo
Flinder’s Ranges
The Grampians

The flora was able to adapt quite well to the change in climate and it was able to diversified continent-wide.

The most recognized plant in Australia, the Gum Tree or the Eucalyptus, was thought to have evolved during the dry periods on the continent and became a major part of the continent’s landscape. The drought helped to spread and diversify the Eucalyptus across the country. Today, there are over 700 species of Eucalyptus, most of which are native to Australia.

Classification of Australia’s Flora

The flora of Australia are unique and approximately 80 percent of their native species are exist only in Australia while 30 percent of the native genera exist only on the continent. With its isolation, many scientists thought of it as a desolate area with no good flora species of its own. This caused Australian flora to be classified in one of three ways:

Indo-Malaysian – which were the northern rainforests
Antarctic – the southern rainforests
Australian – Eucalyptus and Acacias

Most scientists thought that most vegetation in Australia either came from the northern countries of Malaysia, Indonesia or Asia and, in the south, from Antarctica.

The classifications have been changed and there are now two categories:

Relictual – which are the rainforests
Australian – which are localized flora

The flora of the continent evolved from the relictual forests.

There seems to be a common ancestry suggested by similarities that exist between Australian and Indian rainforests. The rainforests in India and Australia have 47 genera in common. Australia also shares 41 genera with Papua New Guinea. Along with this shared ancestry of the rainforests, there are also some species that migrated to the area due to seeds being transported by the wind, such as some orchids.

Flora Evolution From the Rainforests

The climate in Australia during the Tertiary period was mild and most. The entire continent was most likely covered with vegetation similar to that of a subtropical rainforest. The forests evolved from Gondwanan rainforests and they were the predecessors of the rainforests of Madagascar, India, Africa and South America. The flora of the Australian rainforests at this time is often referred to as Pan-Australian.

The proof that the entire continent was covered by rainforest comes from fossils that were found of the only holly that is native to the country. This holly, known as Ilex arnhemensis, now only grows in the lowlands forests in northern Australia, but its fossils were found all over the continent.

As the climate began to change, the vegetation evolved. While the subtropical vegetation persisted in some areas, a cooler climate rainforest grew as well. Areas with soil poor in nutrients saw the evolution of eucalyptus and acacias species. The idea that Australia was the origination of the Gondwanan rainforests is due to the number of primitive plants that still exist today in the forests, especially in Queensland.

There are approximately 19 plant families that are considered to be among the most primitive plants in the world. Of these 19, 13 of them are found in Queensland. This gives Australia the distinction of having the highest concentration of primitive plant families found throughout the world. One of the world’s oldest vascular plants, the psilotum nadum still grows in Australia today and it is a native of the Queensland area.

Sclerophyllous, or dry-country, vegetation is the most dominate type of vegetation on the continent and it was evolved from the Gondwanan forests, including Eucalyptus and Acacias. As these two species began to become more dominant throughout the landscape, the rainforests began to decline. They were able to thrive because they adapted best to the frequent fires that began to occur in Australia. There are approximately 900 species of Acacia in Australia, along with the nearly 700 species of Eucalyptus.

Human Impact on Flora

Humans have had an impact on the flora of the country as well. Aborigines, which colonized Australia about 38,000 years ago, are thought to have made a contribution to the evolution of flora on the continent. These natives of Australia were known for their habit of burning, which was noted by the increase of charcoal deposits in fossils recorded at around the time period. The burning helped to renew the bush areas of the continent.

Fire-stick farming, as it was called, by the Aborigines is thought to have destroyed the Araucarian forests and restricted Dacrydium to Tasmania. This practice, along with a dry climate, may have also have contributed to the high degree of dry-country vegetation that evolved Australia. In order to survive and thrive, many species had to become fire-resistant or fire-dependent.

European Settlement Impact on Flora

The arrival of Europeans to the continent in 1788 also contributed to the evolution of flora in Australia. Agricultural practices that were brought over by Europeans made significant changes in plant life. Despite the fact that Aborigines managed to live off the plants and animals native to the continent, the British who arrived thought the land was too barren and the climate too hostile to supply them with an adequate amount of food.

The settlers knew they couldn’t sustain themselves solely on imported goods because it took eight months to cross the ocean from England to Australia. The ships of the First Fleet, lead by Captain Arthur Phillip, brought over livestock, plants and seeds to ensure the survival of the British settlers. Among the plants were Prickly Pear and Spanish Reed.

After his arrival, to help make sure the settlers could arrange, Capt. Phillip ordered that the land surrounding Sydney Cove be cleared so they could start farming in order to raise crops. Many of the trees cleared were Eucalyptus trees. Even though they had several years were the settlers were on the verge of starvation because they were unfamiliar with the climate and land, by 1800, they were beginning to be able to be self-sufficient and grow enough crops to survive. However, this progress had a negative impact on the flora, as well as the natural resources, of the area.

The British did import several species of plants to Australia, including the Scotch thistle, the Prickly Pear and blackberry bushes. These plants often overtook the area they were planted in and impacted the native flora species of those areas. The Prickly Pear and blackberry bushes are considered noxious weeds in many areas of Australia and the Scotch thistle proved itself to be an invasive plant, growing in and taking over the south-eastern coastline of the country.

Since plant destruction and farming practices destroyed many native species, soil erosion became a problem after the British began to settle the country. Overgrazing also led to many plant species being destroyed or decimated as well. Soil compaction, the change in soil salinity and waterway pollution caused by agricultural practices introduced to the country has lead to the further evolution of the flora of Australia.

The Impact of Introduced Species

Since the migration of Europeans to Australia, over 27,000 different plant species were introduced to the continent. These introduced species outnumber the number of species that exist in the country, which is approximately 24,000. Many of the introduced species of flora have proved themselves to be invasive and have done their part to wipe out native species by overcrowding their habitat. Some of these plants are now considered weeds and approximately 10 percent of the invasive flora species have established themselves, meaning they now thrive in the wild.

It can take some time before introduced species of plants are identified as invasive or as weeds. For tree plants, it can take hundreds of years for them to cause problems after they are introduced into an area. However, with annual plants, some became problems only 10 years after their introduction onto the continent. Four known native species have were destroyed by invasive flora choking them out and another 57 are considered to be in danger of extinction.

Some plants introduced to the continent as crops, including wheat and barley, have never established themselves and need to be sown every year in order to grow successfully. However, horticulture in Australia has introduced more invasive species of plants than any other activity on the continent. Some exotic species that have been imported to decorate houses and gardens have found there way into the countryside and have depleted the soil and choked out native species.

Modern Flora in Australia

According to the Australian government, there are approximately 20,000 different types of vascular plants and 7,700 non-vascular plants growing in Australia. These plants include living fossils such as the grass tree and cycad palm. They also include a wide variety of wild-flowers, of which the kangaroo paws is one of the most prevalent throughout the country.

The most prevalent vegetation in the country are the types that have adapted to the dry climate of Australia in areas where the land has not been cleared for growing crops. The most dominant vegetation is the hummock grasslands, which accounts for 23 percent of the vegetation in the country. The hummock grasslands are present in Western Australia, South Australia and the Northern Territory.

Conservation efforts are being made to help Australia’s native flora to survive the invasion by introduced species. Ridding the countryside of invasive species costs the country over $3.5 billion each year, not to mention the damage done to native plants. Australia has a vast array of native species that have evolved over the centuries, but imported plant species can quickly decimate those native plants.

While weather conditions and natural phenomena have had a great impact on how flora has evolved on the Australian continent, the impact of man has also greatly influenced the evolution of flora as evidenced by the evolution of plant species in Australia. Fortunately, there are many people who have begun efforts to try and lessen the impact made by man by preserving native species and fighting the impact of introduced plant species.

Over the centuries, many beautiful plants, flowers and trees have evolved on the Australian continent, giving the country a very diverse range of flora. With the efforts of the government and preservation groups, the native flora of Australia will continue to thrive.

Useful links:
Australia: The Land Where the Wild-flowers Really Grow
Planting the Seeds of a Healthy Environment
http://www.environment.gov.au/
http://www.dfat.gov.au/facts/flora_and_fauna.html

Australia: The Land Where the Wild-flowers Really Grow

Blessed with an envious abundance of varying growth environments, there are in fact about 24 000 different species of Australian native flowers and plants.

The parched desert conditions of the centre of the country may have only the sparsest and heartiest vegetation, but other areas of this majestic country are nutrient rich, lavishly hydrant and exceptionally fertile. The perfect combination of elements to bring forth wonderous plant life, vegetation and foliage. From gum trees to tomato bushes, Australia has a complete landscape of plant life to provide food, medicine and building materials.

Australia has many coastal plants and shrubs, forested areas and bush land. Different regions of the country provide unique habitats for home grown plant life. Some of the native species to Australia have often been harvested to plant in other parts of the world.

The results vary greatly when Australian plants are grown in other countries around the world. Some plant life and vegetation stubbornly refuses to grow at all outside the borders of its home and native land. No matter how well acclimatized the new environment may be to replicate familiar conditions; there are many varieties of herbs, trees, flowers and plants that will never be found in any part of the world except Australia.

Fortunately, there are just as many other plants, trees and bushes, that have discovered how to thrive away from home. Some of the most popular and well known Australian species have taken on a completely new life. These plants, trees and shrubbery are adapting to new climates, soil and water, and unusual weather conditions with such gusto that the Aussie natives have taken over the landscape, refusing to let anything else grow in the same habitat. (A regrettable example can be found in the everglades of Florida.)

Whether at home or far and away, the different species of Australian native flowers and plants are clearly among some of the most sought after flora in the world. A large number are regularly tested and studied by scientists for natural properties that promote the health and well being of other plant life, animals and even humans.

A Few of the More Well Known Species

With so many varieties of plants, it is impossible to list them all here. However, there are some very well known species that are used in different applications around the world that many people are surprised to learn are native to the soils of Australia. Names of plants, trees and flowers you hear every day may indeed be from the land down under.

Eucalyptus

When we think of eucalyptus, koalas quickly come to mind. Some varieties of eucalyptus leaves are the only food that is eaten by many types of koalas. However, the eucalyptus has a diverse amount of uses for its approximately 700 different native grown species.

Offering a humble home for a host of wildlife from birds to small animals, the eucalyptus is a variety of gum tree. The oil from the large leaves is used in many medicinal products as well as skin care and beauty products.

Vapour rub and cold remedies take advantage of this natural expectorant to bring relief to head and chest colds, to help break up nasty congestion and phlegm. Muscle creams and joint rubs also use eucalyptus because of its anti-inflammatory nature, which provides relief for both swelling and discomfort.

Eucalyptus is anti-fungal, a trait discovered by early aboriginals who used the leaves to treat wounds. It is also used as an antiseptic, or the leaves are brewed into a tea to help bring down a high fever.

As a hardwood, the eucalyptus is an icon in the Australian timber industry. As far as burning it as firewood, the fragrant aroma of eucalyptus wood on a crackling fire brings a tranquil serenity unmatched by other burnable woods. The pleasant scent of the eucalyptus can be found in many other products used around the home, unmistakable and distinct as an Australian classic.

Melaleuca Trees

Not quite that familiar with the melaleuca tree? It comes in a variety of sizes from the very large 80 foot trees to smaller ones that are merely a few feet off the ground. Quite likely everyone in Australia is familiar with this densely populated native tree, but in other parts of the world, this tree is known by different aliases.

Sometimes called the paperbark tree, the smaller melaleucas are best known throughout the world as tea trees. The oil from the tea tree is among the most widely used natural essential oils in the world. Now have you heard of it?

Anti-fungal, anti-inflammatory, anti-viral and antiseptic, the medicinal uses of tea tree oil are still being discovered and expanded upon practically every day. The natural healing properties can be found in skin care products, antiseptic washes, shampoos, body washes, skin creams and even toothpaste and mouthwash.

In recent years, tea tree oil has been singled out as a natural, non-pesticide treatment to get rid of head lice. Although there has not been enough scientific research conducted to verify how and why this appears to work, parents around the world swear by it.

Eremophila

While many of Australia’s native plant life is often cultivated to grow in other parts of the world, the eremophila is quite loyal to its homeland. There are perhaps 214 different varieties of the eremophila, all of which can be found exclusively in Australia.

Also known as emu bushes, the oil from this tree is another popular essential oil. Emu oil has a wide variety of uses but its most commonly used as in topical skin care products. Known for its intense rehydrating properties, emu oil is a favourite ingredient in natural body washes, shampoos, soaps and lotions.

Kangaroo Paws

This lovely plant is an Aussie relative of the lily family, whose scientific name is haemodoraceae. Over 100 species are in this variety of small plants, which have leaves that stretch out about 3 feet high and wide. The plant earned the name kangaroo paws because of the pretty flower bells, which are long and slim, looking very much like the paws of a kangaroo. The flowers do not carry much of an aroma, but are quite pleasing to view and ideal for certain types of birds.

Other Flowering Plants

Australia has a huge selection of beautiful flowering plants that are often cultivated in gardens around the world. Bright, vibrant colours, delightfully shaped petals and hearty growth make many of the native flowers of Australia a gardener’s paradise.

Many of Australia’s plants and flowers make great features in the garden, while others are planted to attract butterflies or birds. With so many flowers, there is hardly a lack of choice for adding colour and texture to any display.

Some popular flowers include several members of the mint bush, such as the seven different species of the hemiandra and forty varieties of hemigenia, all of which are exclusive to Australian soil.

In fact, for almost every major plant family, there are at least a few varieties that can only be found and grown in Australia. Daisies, acacia, hakea and many flowering pea plants are native to the country and keep their roots planted in home soil.

Weeds are Plants Too!

What is a garden without a few weeds? Plant life in Australia has many beautiful blooms and lush forestry, but it also has some rather interesting weeds. Many of the plants that were considered flowers a couple centuries ago are now in the weed category.

Keep in mind, a weed is a plant that has no purpose. No fragrance to enjoy; no beauty to admire; no benefit to the soil. Sometimes weeds are a magnet for other undesirables such as plant-destroying insects. James Russell Lowell once referred to weeds as “no more than a flower in disguise.” In the case of many of the weeds found in Australia, that is a fitting description.

Several types of plants in the wattle family such as cootamhundra, golden wreath and queensland silver, have grown too dominant to be considered anything other than a weedy nuisance. Even some species of melaleuca have overgrown their welcome is some areas around Victoria, making them treacherous to other plants trying to grow in the bush.

Interestingly enough, some of the plants that originated in Australia and were harvested and seeded in other parts of the world, have become to overbearing for their host environment and been classed as weeds. Therefore, anyone looking to plant an Australian garden would be wise to avoid planting acacia, melaleuca, a.cyclops and other native Aussie plants. These are among many of the greeneries that are so adaptable to new environments that they become dominant to the point they bring peril to the growth of other plants.

Fire Proof Plant Life

The threat of bush fires is ever dominant in many parts of the Australian landscape. Most plants and bushes will burn quickly and spread easily to others in their path. However, there are some very hearty plants, both native and non-native, found in Australia that stand tough in the face of fire.

That does not mean these plants will never burn at all. It means numerous studies and tests have been performed to see how resistant they are to burning. Fire resistance means it takes a longer time for the plant to ignite. Due to their natural ability to withstand the heat, Australians in high risk fire areas are recommended to plant these varieties around their property. Plants will not stop the fire from reaching a person’s home, but it might slow it down enough to reduce the damage.

Some of the fire proof Australian plants recommended for planting include many types of saltbush, including coast saltbush, spreading saltbush, silver saltbush, old-man saltbush and several others. Rounded noon-flower, creeping emu, bottle bluebush, frosted goosefoot, white cedar as well as all twin leaf plants have been tested and found suitable for fire prone areas.

Ground cover is just as important to keep a fire from spreading, and there are many plants recommended that help keep the fire from engulfing the area. Silver mulga, narrow rock-fern, spotted gum, silver wattle, water bush, blackwood and dozens of other low growing ground plants will not burn when the first contact with fire reaches them. However, due to the nature of fire, these plants will very likely lose all their moisture content during a fire, at which point, the dried leaves will become vulnerable to flame.

Australia’s Garden of Delights

An intricate source of pride for so many, the many botanical wonders that cast themselves upon the landscape are a treasured garden of delights. Very few countries can boast so many native specimens. By comparison, England is barely a garden country at all, with only about 1700 different plants that are native to the country. Of-course, finding new, undiscovered plant life in Australia’s vast forests and bush land does happen from time to time.

Will there ever be an exact number? It is highly unlikely. Some species have become endangered due to environmental changes. Fires have greatly reduced some fragile greenery, and the introduction of non-native plant life over the centuries has pushed out some weaker native species.

Nevertheless, Australia will continue to be one of the best places to look at when it comes to finding variety, colour, fragrance and diversity in all forms of plant life. Scientists will continue to explore the vast properties and characteristics of different vegetation to bring new medicine to the human race.

We are majestically humbled when we look at the immensity of the different species of Australian native flowers and plants. Indeed, it does make the human race rather insignificant by comparison.

Whether strolling by the garden gate, resting beneath a shady tree with a good book, or filling the air with aromatic presence of eucalyptus, there is no part of the world that has not been touched, changed and made better by the wonder of Australian plant life.

Useful links:
Australian flora | australia.gov.au
Australian Native Plants Society (Australia)
Florabank
Greening Australia
Planting the Seeds of a Healthy Environment