Understanding native vegetation
Introduction to the descriptive terminology used for describing natural groupings of plants
Vegetation varies across the landscape
Some plants will only grow in areas with specific conditions such as rainfall and soil type
What is a vegetation association?
A vegetation association is a group of plants which occurs in association with soil types, rainfall and other climatic conditions along with animals, birds and insects. The plants in these areas are there because they are best at exploiting the conditions available to them. A vegetation association is usually named after the most dominant canopy species occurring in the area, which is most often the Eucalypts, e.g. Grey box grassy woodland or Stringybark forest. The terms woodland and forest refer to the organisational structure of the vegetation, sometimes called the vegetation class. A forest consists of taller trees generally more than 15 metres high which are quite close together, a woodland has fewer large trees and more medium size trees to 5 metres which are a lot further apart, giving a more light and open appearance. Woodlands are often grassy at ground layer.
Vegetation communities can in many instances be correlated with soil types and topography. Over thousands of years the plants and animals living in these associations have started to become dependant on one another for food, pollination, pest control, water supply and habitat provision. There are certain animals which show distinct preferences for particular vegetation associations and individual plants. On the other hand there are a number of species for which a variety of habitats and vegetation associations are essential to their survival. Therefore it is important for us to give consideration for all types of vegetation associations, when we think about conservation. We can often easily work out what the vegetation in an area was like, based on what still grows in our National Parks and reserves. Sometimes entire regions have been extensively cleared, leaving little of the original vegetation, making it a lot harder to determine what was once there. In this case we can often work it out from tiny patches of vegetation left on roadsides or single trees left in parks or residential gardens. Combining this information with soils and rainfall data will usually enable us to predict what the vegetation once looked like.
Why is this information important?
Many of the serious environmental issues facing us today e.g. dryland salinity, loss of biodiversity, loss of water quality, can be attributed to the clearance of indigenous vegetation from the landscape. In order to address these issues, revegetation is the management tool most often implemented. To ensure that our revegetation projects are successful, we need to be aiming to reinstate the plants which once occurred in that area as they are best suited to the local conditions and provide the best habitat for local indigenous species. Learning about what used to be there (and what shouldn’t be there) allows us to make informed decisions when managing these areas.
As is the case in nature, things are rarely black and white. The concept of a vegetation association is based on human observations and used to help us to understand why plants occur in groups and why vegetation changes across the landscape. There will always be plants which ‘break the rules’ and grow in areas which are seemingly completely unsuitable for their well-being. Lines on a map showing the boundaries between vegetation associations will more often than not represent a very broad, fuzzy line in nature and should not be interpreted as absolute.
About the vegetation associations map
On this website you may find a map of the pre-European vegetation associations. The dominant canopy species are listed at the beginning of each information box. Where a +/- appears, the species appearing after this symbol occurs inconsistently across the range.
As vegetation associations are most often determined by soil type and rainfall, this information is also included for each area. The vegetation class and a description of the typical landscape is also indicated. The vegetation around a creek or river (the riparian zone) is often a little different, so the typical canopy species for these zones is also indicated. Further information about other plants occurring within association can be found on the plant identification charts at the back of this folder.
Introduction to botany
Botanical studies organise plants into genera families and species
Plant families are often very logical and easy to learn
Using Latin names when describing plants tells you about the plant’s family
What is botany?
Botany is the study of plants. Botanists collect plants into ‘families’ based on similar characteristics. All members of each plant ‘family’ have similarities in their flower structure and are thought to have descended from a common ancestor. Note that the family names of plants usually end in ‘CEAE’ and are always capitalised when written. For example, the MYRTACEAE family is one of the largest families of Australian plants. The word MYRTACEAE comes from the Greek word ‘Myron’ meaning perfume which refers to the characteristic fragrance of many members of the MYRTACEAE family. Some of the main characteristics of the MYRTACEAE family are:
leathery leaves which are dotted with transparent oil glands
hard, woody fruits capsules which open at the top to release many tiny seeds.
Each ‘family’ is further divided into a number of ‘genera’ and these genera further divided into ‘species’ which have more similar genetic characteristics. Some of the genera in the MYRTACEAE family include Eucalyptus, Melaleuca and Leptospermum. Ultimately each group of plants which appear to have the same structures are given the same name and no two different species may have the same name. The Eucalyptus genera has more than 600 species. A couple of local species include Eucalyptus camaldulensis (River red gum) and Eucalyptus leucoxylon (SA blue gum).
This system of classification and naming of organisms is used for all living things all over the world e.g. humans are Homo (genus) sapien (species).
The use of Latin and Greek words ensures consistency of names regardless of the language of the user. The common name often derives from a feature of the plant, e.g. Grey box relates to the colour and type of bark, River red gum relates to where the tree prefers to grow and the colour of the timber. Common names for birds are often formed in the same way e.g. Yellow-tailed black cockatoo and Red wattlebird. Many people find common names a lot easier to remember but common names are not always useful for telling us about the family or ancestry of an organism. For example ‘Kangaroo thorn’ does not tell us that this plant is a type of Wattle or Acacia. Common names can sometimes vary between botanists and publications. Occasionally two different species may be given the same common name or there may be more than one accepted common name for the same plant. This can be a problem if we are trying to work out precisely which plants should be growing in a particular area. Using the botanical name ensures that there is no confusion about which species is being discussed.
Monocot or dicot?
Botanists use many attributes of plants to assist them in identification. In South Australia we have mostly flowering plants, or angiosperms. Of the gymnosperms, or non-flowering plants there is only one, the CUPRESSACEAE which includes the native pine genus, Callitris.
The first step used to identify flowering plants (angiosperms) in almost any plant identification book ever published, is to determine whether the plant is of the class DICOTYLEDONEAE or MONOCOTYLEDONEAE. This subdivision is based on whether the embryo (seed) of the plant will sprout one or two cotyledons (leaves) when it germinates.
How to distinguish monocots and dicots
Monocots (short for ‘monocotyledon’, ‘one leaf’) are flowering plants, with one vertical grass-like baby leaf. They include local indigenous plants such as Common vanilla lily, Garland lily, Kangaroo and Wallaby grasses, as well as orchids, bamboo and palm trees (including bananas). Most of the world’s cereal crops such as wheat and barley are also monocots.
Identification of local indigenous plants
The parts of plants used for identification
The parts of a plant most used in plant identification by the inexperienced plant observer (non-botanist) are the size, shape, buds, flowers, fruit, bark and leaves of a plant. The usefulness of these attributes for identification depends greatly on the plant being identified. The key to becoming good at identifying different plants is working out which attributes of the plant vary the most between different plants. For example, one of the most defining features of the different local Acacia (wattle) species is the size and shape of the leaves. For Eucalyptus, the fruits (gum nuts) will often vary greatly between different species, making this the most useful tool for identification. For many of the smaller shrubs and ground layer plants, it is the flowers which tend to be the most noticeable and varied feature. Despite these distinctions, it is often necessary to look at a combination of plant attributes to make a positive identification. Even then it can still be very challenging, especially if there are many species of the same genus in a particular area.
Thankfully, there are many excellent plant identification resources to aid with plant identification. Many of the plant identification resources available for use base their defining techniques on one or more plant properties. For example Ann Prescott’s It’s Blue with Five Petals uses flower colour as its defining feature.
Many of the resources tend to cover whole of South-eastern Australia, South Australia or the whole of the Mt Lofty Ranges. Opening a book of Australian Eucalypts, to discover that there are more than 500 species, can be quite daunting. Convenient for us there are only about 90 which are indigenous to South Australia and from these only about twelve which are indigenous to the Onkaparinga catchment area. For this reason it is better to have the most local resources possible to reduce the pool of possibilities.
See the recommended resources for some good local publications. Note that all of the referrals to vegetation in that activity is really only relevant to patches of remnant vegetation most often located on roadsides and in reserves. Many, if not most of the Australian natives historically used in amenity plantings in streetscapes and gardens are not local, but most often indigenous to Western Australia or the East Coast of Australia. Attempting to find a Western Australian native in a book about South Australian plants can be very frustrating! Stick to remnant patches for plant identification activities.
A good starting point for plant identification is to try to identify to genus level, as this is often very distinctive. Once students can confidently identify an Acacia, Eucalyptus, Hakea or Banksia, etc, identifying the species within that genus will seem a lot simpler.
Acacia: A widespread genus
Acacias (or Wattles) are the most widespread genus of Australian native plants. The Acacia genus is also indigenous to South Africa. Species within the Acacia genus are often best recognised by their leaf shape. Generally the Acacia genus is very robust and being of the LEGUMINOSAE family (legume), is able to improve soil nitrogen levels. It is used extensively in revegetation projects due to its ability to colonise areas of bare ground and recent disturbance. However this, resilience can also make them a formidable pest plant if they are introduced to areas outside their natural range.
Plants as resources for local wildlife
The buds, flowers, fruits and seed of our local native plants are generally the richest source of food for many of our visible wildlife such as insects birds and mammals. Many of us have observed Honeyeaters frequenting tubular flowers in suburban gardens, Yellow-tailed black cockatoos eating the seeds of a Banksia or groups of Parrots eating the flowers of Eucalypts and dropping the leftovers all over the ground. Unfortunately for these animals, plants do not produce the specific resources needed all year round. Many animals must travel to find enough resources. Historically, animals are probably well-accostomed to travelling for their food but modern times have no doubt made life harder through:
the loss of large tracts of the right kind of resources (vegetation) and
barriers in the landscape such as roads, fences and treacherous cleared landscapes where smaller animals have little shelter or protection from predators.
While we often associate spring with a flush of flowers and life, there are many plants which provide all-important resources throughout lean times in summer, autumn and winter. Sometimes the timing and duration of flowering will vary in an area due to seasonal factors such as rainfall, soil fertility and temperature. Learning when and where our vegetation provides the resources needed for wildlife can teach us a lot about why populations of species decline or explode.