According to my grandad, a weed is simply something that grows where you don't want it to. So, the most beautiful rose could be a weed, if it's growing in your brussel sprouts!
That is similar to the approach I've always taken, whereby I'm happy to have dandelions in my lawn, but not in my flowerbeds. As a result, I may need to do more weeding than I would like, but I get the benefit of beautiful flowers with the colour of sunshine and the smell of summer. Plus my daughter gets to enjoy trying to tell the time with the ‘dandelion clock’, or trying to catch the ‘fairies’ as they float away in the summer breeze.
In short, the old way of looking at things meant that something could be a weed to one person, and not to another. However, I do understand that the definition of a weed is a bit more complicated than that. Here in Australia, I've found that there are so many ways of defining a weed, that each municipality, state and territory has their own specific weed lists. As this is all fairly new to me, I've done some research and thought I'd share it with you all. I'm sure that someone has probably done something similar in the past, or that most of you already know this, but I didn't so here goes...
Generally, a weed is a plant which has become, or has the potential to become, invasive. Invasive plants are those that are not native to the area in which they have become naturalised. This means that plants that are indigenous to Australia, but have become naturalised outside their native habitats, could be considered invasive. In Victoria, the Cootamundra Wattle and Sweet Pittosporum are examples of this. Generally they must have spread through more than one area and either be a threat or a potential threat to the environment to be considered invasive. Often, this means that they have a detrimental or destructive effect on animal and plant species that are native to that area. However, it could mean that they have an adverse effect on the health of humans or, as is more likely, they could result in crop or stock losses (interesting to note that these crops or stock could themselves be considered invasive based on the general criteria).
So, looking at Australia as a whole, there are two terms that everyone should be familiar with. These are 'Noxious Weeds' and 'Weeds of National Significance' (WoNS).
Noxious Weeds are those that have been legally declared as such by the various State or Territory Governments and this usually means that their sale, distribution and growth are restricted. These are not the same in every state, though there may be some weeds that have been declared noxious in most.
WoNS are those weeds that have been investigated by the Australian Weeds Committee: a national initiative set up to identify and resolve weed issues at a national level in Australia. Each State and Territory nominated weeds that they believed constituted the most serious weed problems in Australia. These weeds were then assessed against four criteria (invasiveness, impact, potential for spread and socioeconomical or environmental impact) using a variety of data analysis methods. This resulted in a top 20 list of WoNS, which will be reviewed on an ongoing basis. The committee admits that the time and resource constraints, number of weeds nominated and lack of data means that the final list will be debatable, but this is an ongoing project and no doubt the list will change in future.
There are also 'Sleeper Weeds', which are those that may remain benign for many years and only become an issue after a specific event, such as a flood or bushfire. A list of these can be found on the Government's Weeds site.
Now, if you look at Victoria alone, you might also come across the following categories of weeds:
State Prohibited Weeds - These weeds are either currently present in Vic and pose a serious threat, or they could pose a serious threat should they invade. If they do exist in Vic, infestations are likely to be small and they could reasonably be expected to be eradicated. The Vic govt is responsible for eradication, but could direct landowners to prevent their growth and spread.
Regionally Prohibited Weeds -These are not widely distributed in a region, but are capable of spreading. It is reasonable to expect that they can be eradicated and land owners, including public authorities, must take all reasonable steps to eradicate such weeds from their land.
Regionally Controlled Weeds -These are usually widespread and have an impact on a particular region. Land owners are responsible for taking all reasonable steps to eradicate such weeds from their land.
Restricted Weeds -The trade of these plants, or any part of them which could propagate, is prohibited. The trade of materials, which are contaminated by these plants, is also prohibited. These plants are those which could pose an unacceptable risk of spreading in Vic, or other states, and which could pose a serious threat. The plants in this category, would fit under the definition of noxious weeds. These plants are also considered Weeds of National Significance (WoNS).
Noxious Aquatic Species - These are plants which pose a serious threat to the aquatic environment, human health, or fisheries. It is an offence to bring these into Vic, or to sell, transport, possess or release them.
If you want to find out about the plants considered as Noxious Weeds in your area, then you can use the Weeds Australia website to see everything for your State or Territory, or narrow it down to areas within the state. There are in fact downloadable PDFs with a list of all Noxious Weeds in Australia and the regulations in each state regarding weeds, also available from the Weeds Australia website. These are up to date as at October 2010. You can check out the WoNS list there, or have a look at the Government's Weeds website which also carries it.
The Government's Weeds site has loads of easy to follow information on what defines a weed, where they come from and why they cause problems. It also has a list of 28 species which form the National Enviromental Alert List, the 6 Species Targeted for Eradication, info on how to identify and manage weeds, a section that provides top tips to gardeners and other interested parties, plus lots of interesting booklets and reading material (including guidelines and manuals on the WoNS and alert list weeds). It is well worth a look and I'm pleased to report that my dandelions are not on the weeds lists, as far as I can see!
There is also an excellent campaign called Grow Me Instead. This is an initiative of the Nursery & Garden Industry Australia, which originally started in NSW, and aims to encourage gardeners to use some of the suggested replacements (often native plants) instead of certain invasive species. They publish handy little booklets for gardeners and I’ve found the one for Vic to be really useful.
In fact, shortly after moving here we got a copy of the booklet and were fairly shocked to discover that the beautiful flowering plants everyone in the area has in their gardens, including us in abundance, is a declared weed! This is Agapanthus, which is so invasive in this area (Shire of Yarra Ranges) it’s been targeted for Wipeout. Arum Lillies are also a problem and seem to have naturalised in most of the gardens around me (particularly over the road where the entire front yard of about 6x12m is covered in them!). Confusingly however, both are still available at most garden centres because they are not restricted weeds.
If you live in the Shire of Yarra Ranges, or in a bordering municipality, then you may wish to visit the Greener Living pages of the council’s website. From here, you can find information on weeds in the area, those targeted for the Weed Wipeout program and also links to the plant communities that exist, or once existed, in your local area. We’ve found both the Local Plant Directory and the Intramaps site to have loads of great info when planning our garden. Using the Intramap service in particular is great as it allows you to obtain a list of the Indigenous Vegetation and the accompanying revegetation lists for your immediate area.
I hadn’t looked at these lists in a while (I’ve been busy with a toddler and new baby!), but now we’re able to get out in the garden more, we’re using these lists to help us establish a fernery and to reintroduce native plants to our small bit of heaven.
Hopefully, it will also help me work out what species all our gum trees are!!
Weeds Australia – http://www.weeds.org.au/index.html
The entire Noxious Weeds list – http://www.weeds.org.au/docs/weednet6.pdf
State and Territory Regulations (plus keys for the Noxious Weeds List) – http://www.weeds.org.au/docs/weednet6doc.pdf
Government's Weeds site - http://www.weeds.gov.au/index.html
Grow Me Instead - http://www.growmeinstead.com.au/
Shire of Yarra Ranges Green Living pages (includes links to the Weed Control section) – http://www.yarraranges.vic.gov.au/Residents/Greener_Living
Shire of Yarra Ranges Local Plant Directory – http://www.yarraranges.vic.gov.au/Residents/Trees_Vegetation/Yarra_Ranges_Plant_Directory/Yarra_Ranges_Local_Plant_Directory
Shire of Yarra Ranges Intramaps site – http://www.yarraranges.vic.gov.au/eServices/Online_Maps