ten terrible weeds in my garden

The Australian government website Weed Identification and Information makes it easy to identify weeds. On this Most Unwanted list I found 10 plants that grew in my garden. Most of these came as no surprise, but a few of them had been welcomed into the garden because I was not aware that I was harbouring dangerous bio-threats to the nation's ecological security.

The weeds I didn't know were weeds mostly became problems in the wider ecosystem when they escaped from their garden settings. These garden escapees were described in an important 2005 report called  Jumping the Garden Fence. It is about the invasive plants that are for sale in Australian nurseries and helped to raise awareness of this problem.

Here are the Terrible Ten:

African lovegrass

1. African lovegrass, or Eragrostia curvula is one of the reasons I gradually replaced the grass in my garden with beds and stone paths. Weeding the lawn became boring and ineffective. The feathery seed heads just kept coming. They still appear in the garden beds, but not in such alarmingly high numbers. It is a South African native, originally imported as a pasture grass and now has naturalized all over Australia. I'm sure it was present when we moved in in 1979, when the back garden was just a field of weeds and rubbish such as rolls of barbed wire.

Blue periwinkle

2. Blue periwinkle, or Vinca major was growing in my neighbour's garden when we first moved in. I loved the beautiful bright blue flowers, and when it grew under the fence I welcomed it. Soon after this a gardening friend warned me that it was a terrible weed and once it got established, would take over. I took the advice and carefully dug it up and disposed of it whenever I saw it. I still see it sometimes but not often. Interestingly, its name comes from the Latin word for 'conquer' because of its aggressive ferocity. A garden escapee, it now invades bushland and waterways, smothering native plants. It is native to the Mediterranean region.

Cane needlegrass

3. Cane needlegrass, or Nassella hyalina, like African lovegrass, was present in my garden when it was a field of weeds. Of course, by clearing, disturbing and enriching the soil, I was inadvertently encouraging it to naturalize in the garden. And it did. Without the grass to lurk in it became more visible and more or less containable. But even among officially classified weeds this one is really bad, one of 28 weeds on the National Environment Alert List. Cane Needlegrass, native to South America, so far is only present around Melbourne. But it is spreading, by virtue of its sticky seedheads which attach themselves to clothing and animals, and the fact that it is drought proof and forms dense vegetation that threatens biodiversity.

Coastal tea tree

4. Coastal tea tree, or Leptospermum laevigatum was a surprise to see on the list. From the beginning I was attracted to groups of tea trees. I love the way their trunks bend and twist, their ridged bark and their lovely flowers. I was unaware of differences between varieties. There used to be a wonderful pioneering nursery called Austraflora, specializing in collecting, propagating and publicizing native plants as garden specimens. I know I bought L. laevigatum there about 25 years ago because I have the label. There are several types of tea trees naturalized in my garden. Some keep seeding themselves which used to please me. But now I realize those must be a noxious weed I suppose I had better stop accepting the uninvited seedlings. Especially in my nature strip on the street where three specimens recently appeared. This example shows that not all weeds are immigrants from abroad since this shrub is a native of coastal areas of Victoria and other states. In fact, I now realize why I love them so much. They are associated in my mind with idyllic childhood beach holidays.
 

 

Common sowthistle

5. Common sowthistle, or Sonchu oleraceus, is a supremely adaptive survivor. Native to Europe and Asia, it is widespread and common here and in many other places. I certainly see it everywhere the ground has been disturbed.  Described officially as an invasive weed, this is definitely a weed with positive attributes. The leaves are as tasty and nutritious as spinach, and the plant has been used medicinally for a wide variety of purposes, including stimulating  menstrual flow, altering liver function and helping with diarrohea, warts, inflammation and fever.  It crops up regularly in my garden but isn't really a problem.

Japanese honeysuckle

6. Japanese honeysuckle or Lonicera japonica - another surprise to see it classified as an invasive weed.! I planted it for its divine scent and attractive flowers to climb on the front fence. That would have been in the 1980s, and there was no problem then in sourcing it from nurseries. This is a common garden plant, one of many that have jumped the garden fence and invaded wider ecosystems.  Japanese honeysuckle is highly prized in Chinese medicine.

Kikuyu grass, image from Wikipedia

7.  Kikuyu grass, or Pennistum clandestinum, is an irritant to me, but a serious problem in the wider environment because it grows fast and aggressively, smothering other plants. It comes from Africa originally, and is readily available for sale because of its tough drought resistant properties. I used to grow it when I had lawn. Since then I rarely see it in the garden. But I continually pull out the runners which cross over the line separating my sandy nature strip from my neighbours' grassy one. I tried to persuade them to give up grass for sand, but it didn't work! Kikuyu is also identified as a garden escapee. It grows from the smallest pieces of rhizome.

Looking glass bush

 8. Looking glass bush, or Coprosma repens, was growing at the side of the house in 1979 when we moved in. It wasn't anything special but I appreciated it for its reliable green display. On two occasions the fence was replaced and it was cut down. It seemed to be indestructible because it always came back. I still regularly find unwanted baby looking glass bushes in the garden and long ago learned not to put the seeds in the compost. A native of New Zealand, this is also named as a garden escapee in the Jumping the Garden Fence report.

Oxalis soursob. Image from Dave's Garden

9. Oxalis comes as lots of different species. They can be identified by their heart shaped leaves and lots of little bulblets. You need to be aware these cannot be pulled out like other weeds. They have to be carefully dug up. Otherwise the little bulblets will drop off, re-seed and you find you have helped them to spread and get even more established in your garden.   Soursob, or Oxalis pes-caprae species is of particular concern in the state of Victoria. It is widespread and invades a broad spectrum of environments - roadsides, forests, grasslands and gardens. Soursob is one the reasons I decided to give uip the lawn. I don't think my dog Potter has ever forgiven me for this decision but it has enabled me to control the spread of this especially persistent weed.

10.  Perennial ragweed, or Ambrosia psilostachya, has only recently appeared in my life. There must have been seeds in the load of sand bought for the nature strip for the transition from grassy to sandy. I have learned that it is best not to get growing mediums from elsewhere if it can be avoided because often you get new weeds or insect pests that way.  I always try to get by without chemicals, even relatively benign glysophate. But I soon realizedthe ragweed was relishing being dug up and I was only assisting it to thrive. So I  started spraying it. It tried to outmaneovre me by growing among wanted plants. This tactic didn't work with me because I am prepared to sacrifice some of the lovely spreading everlastings to achieve the greater good of eliminating this highly successful weed that sets masses of seeds and has long creeping roots as well.  It's native to America.  There is no upside to this plant. Its prolific pollen causes flu like symptoms, contact with skin can cause allergies, and stock wisely avoid eating it.

Perennial Ragweed

Nature strip with weeds as well as desirable plants