Weed

Araucaria bidwillii

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Family: Araucaceae
Genus: Araucaria
Common name: Bunya Pine
ALA reference

This is the only weed species that we intend to retain permanently in the Fort Bushland Reserve. This species is native to the Bunya Mountains and a small area in North Queensland. It never occurred naturally in the Brisbane area and so must be considered a weed tree in the reserve. However removal of these impressively large trees is now rather impractical so it is likely that they will be retained. The trees are monoecious and right now the tips of the branches are festooned with male pollen cones making them look like decorated Christmas trees. The female cones that grow along the branches are wind pollinated and ripen between about January and March. (September 2013)

This is one of the Australian native trees that doesn’t really belong in the Reserve. Its natural range is limited to the area around the Bunya Mountains and the headwaters of the Brisbane River, and to a small area at Mt Molloy, north-west of Cairns. It is a large majestic symmetrical tree attaining a height of about 40 metres with a stem diameter of 1.5 metres. Because of its imposing stature it was frequently planted as an ornamental tree in the late 1800s and early 1900s, which explains why we have so many mature trees around Brisbane. Even from a considerable distance it is quite easy to identify this tree from Araucaria cunninghamii (Hoop Pine) because it appears to have a double pyramidal top. These cone-bearing trees have separate male and female flowers on the same tree. The trees in the Reserve seem to have fruited well this season and the ground under the trees is now littered with fallen cones. Take considerable care when walking under any of these trees for the next month or so because these very heavy cones would do considerable damage if one landed on your head. This tree really does justify its reputation as a bush tucker plant. Australian aborigines travelled from considerable distances to the Bunya Mountains to feast on the nuts and participate in tribal festivities. The nuts are really tasty when roasted but are rather difficult to open because of the tough shell. (February 2011)

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Aristolochia elegans

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Aristolochia ElegansWeed
Family: Aristolochiaceae
Genus: Aristolochia
Common names: Dutchman’s Pipe
ALA reference

This is a Class 3 Declared Pest in Queensland

This is a Brisbane City Council Class C Pest 

In my December Notes I mentioned the large number of seeds that had been left in the soil when we cleared out these vines. Thousands of these seeds have now germinated and they completely carpet many square metres of bushland. Spraying with a herbicide will be the only viable solution. I can only hope that the recent wet weather has caused most of the seeds to germinate so that we don’t have to face this problem over and over like we do with the Rivina humilis (Coral Berry).

(March 2013)

Our last few working bees have focused on clearing the area below the southern side of the picnic ground. The main reason for this is to clear the severe infestation of Aristolochia elegans (Dutchman’s Pipe) creeper. This species is a declared class 3 pest in Queensland. It grows vigorously and smothers understorey trees and shrubs. Some of the creepers that were growing here had stems that were 4 cm in diameter and these vines carried dozens of old mature seed capsules that had already released their seeds onto the ground. It is possible that this patch of plants has already released 100,000 seeds! I suspect that this means that we can look forward to several years of serious weeding in this area to eliminate this pest from the reserve.

As well as smothering native vegetation, this weed is also toxic to the larvae of Richmond Birdwing (Ornithoptera richmondia) and Clearwing Swallowtail (Cressida cressida) butterflies. If these butterflies lay their eggs on the Dutchman’s Pipe vines the larvae die before they reach maturity (unless the larvae feed only on the flowers). The photo below shows their spectacular flowers and an empty seed capsule that contained many hundreds of flattish heart shaped seeds.

(December 2012)

Aristolochia elegans flower

Asparagus aethiopicus

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Asparagus aethiopicusWeed
Family: Asparagaceae
Genus: Asparagus
Common names: Basket Asparagus, Sprenger’s Asparagus, Asparagus Fern, Ground Asparagus
ALA reference

This is a Weed of National Significance

This is a Class 3 Declared Pest in Queensland

This is a Brisbane CIty Council Class C Pest 

One important difference between A. aethiopicus and the other two species present in the Reserve (A. africanus and A. plumosus) is the presence of large numbers of water storage tubers on the roots as can be seen in the photos below. These tubers make this plant incredibly hardy, and almost indestructible when grown in a hanging basket, which is probably why it was so popular some years ago. This plant is also very difficult to kill with herbicides. I’ve sprayed the plants with glyphosate and with Starane and while both cause the “leaves” to go yellow and die off, neither kills the plant. In no time at all the plant sends up fresh new growths.

I’ve found that the only successful control is to dig up the plants. When doing this it is important to understand the structure of these plants. The aerial stems are attached to a short creeping rhizome with a large mass of roots and water storage tubers under the ground. Neither the roots nor the water storage tubers contain any vegetative buds so once they are separated from the creeping rhizome they must die. Hence when digging up the plant it is important dig up the whole rhizome but it doesn’t matter how many roots and tubers are left in the soil because they cannot continue to grow. (July 2012)

Asparagus africanus

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Weed
Family: Asparagaceae
Genus: Asparagus
Common names: Asparagus Fern
ALA reference

This is a Weed of National Significance

This is a Class 3 Declared Pest in Queensland

This is a Brisbane CIty Council Class C Pest 

Three species of Asparagus are common in the reserve; namely A. africanus, A. plumosus and A. aethiopicus. All three are declared Class 3 pests in Queensland which means that they cannot be sold or traded commercially and must be controlled in environmentally sensitive areas. All three are also listed as Weeds of National Significance. The first two have very long climbing stems that grow to a considerable height in the smaller trees.

Asparagus plumosus

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Weed
Family: Asparagaceae
Genus: Asparagus
Common names: Climbing Asparagus Fern
ALA reference

This is a Weed of National Significance

This is a Class 3 Declared Pest in Queensland

Three species of Asparagus are common in the reserve; namely A. africanus, A. plumosus and A. aethiopicus. All three are declared Class 3 pests in Queensland which means that they cannot be sold or traded commercially and must be controlled in environmentally sensitive areas. All three are also listed as Weeds of National Significance. The first two have very long climbing stems that grow to a considerable height in the smaller trees. (July 2012)

Caesalpinia decapetala

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Caesalpinia decapetalaWeed
Family: Fabaceae
Genus: Caesalpinia
Common names: Mysore Thorn; Thorny Poinciana
ALA reference

This is a Brisbane City Council Class R Pest 

This is probably the nastiest weed that I’ve found in the reserve. It is a scrambling shrub/climber growing to 5 or 10 metres up supporting trees. The leaves and stems are covered in very sharp recurved thorns. This plant is the very epitome of a “wait-a-while”. So far I’ve only found two plants, both growing in the northwest corner of the reserve, and they have now been destroyed. I have no idea how they came to be growing there as this plant is not one that anyone could tolerate in their garden.

(January 2013)

Dolichandra unguis-cati

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Cat's Claw CreeperWeed
Family: Bignoniaceae
Genus: Dolichandra
Synonym: Macfadyena unguis-cati
Common names: Cat’s Claw Creeper
ALA reference

This is a Weed of National Significance

This is a Class 3 Declared Pest in Queensland

With Ochna and Lantana, Cat’s Claw Creeper is one of the most damaging weeds in the Reserve. The cat’s claw biological control insects had been released into that area in December 2007 but by December 2008 it had become clear that they were not going to be effective in checking the rampant growth of the cat’s claw creeper. It was obvious that urgent action was needed if we were to save any of the trees or shrubs in that area. By that stage the cat’s claw had already destroyed about 90% of the understorey plants and 75% of the trees. Agreement was reached between the Council and the Alan Fletcher Research Centre that this cat’s claw could now be destroyed. Since then the cat’s claw has been cut from all the trees and poisoned and the ground cover of cat’s claw has been sprayed three times over a three year period with Roundup (glyphosate).

This is without doubt, the most destructive weed in the reserve and has already killed numerous large trees as well as countless smaller trees and shrubs. It is a native of South America and was introduced to Australia as a garden ornamental. It is an extremely hardy and vigorous climber and can tolerate low light situations as well as full sun. It derives its common name from the sharp three-clawed tendril which grows from the leaf base of the climbing stems. As well as climbing the trees it also forms thick mats of runners on the ground and the understorey plants. It produces spectacular short- lived yellow flowers in spring which are followed by long thin seed pods. These pods release prodigious quantities of seed which is dispersed here by the wind. The form we have here has yellow-orange flowers and much longer seed pods than the type species. It has underground tubers which are difficult to remove by digging. The best control method is to cut the thick stems close to the ground and then swab them with 100% Glyphosate within 15 seconds. The vigorously growing smaller plants and regrowth can be killed by spraying with Glyphosate at the rate of 13ml per litre of water. (January 2007)