Worst Weeds

We’ve compiled a set of our most detested weeds – the ones that have been featured in our Weed of the Month segment of the monthly web news.  We’ve organized these by month to help you identify pests by the time of year they tend to be the most prominent.

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Agapanthus (Agapanthus praecox ssp orientalis)

  • The photograph shows an Agapanthus plant growing at the water’s edge in Furness Park:

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  • On the positive side, Agapanthus is drought resistant and good at stabilizing banks.  On the negative side, it is a prolific and hard-to-eradicate introduced weed.  We’d dearly like all our friends and neighbours to dead-head your Agies once flowering is finished,  so seed does not enter the creek system via storm-water.
  • Alternatively, you might consider replacing them with an indigenous plant of similar habits (eg a species of Dianella or Lomandra).  Please see our Useful Links page for details of the local indigenous plant nurseries who will be able to help you with choices.

Spear Thistle or Scotch Thistle (Cirsium vulgare)

scotch thistle

  • Spear Thistle has an erect habit growing to 1.5 m tall.  Its stems and spear-like leaves are very spiny and prickly.  The top surface of the leaf is dark green and rough while the lower surface is white with short, matted hairs.
  • The purple flower-heads are 12-40 mm in diameter and mainly appear in summer and autumn.  The plant is spread by seed using a pappus (a sphere of hairs that aids in wind dispersal).
  • It is a native of Europe, Asia and North Africa – not only Scotland!

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Honeysuckle (Lonicera japonica)

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  • Honeysuckle originally comes to us from Japan.  It is a vigorous scrambler that can smother indigenous ground cover, strangle standing plants and is hard to eradicate.
  • The picture above (taken by Friend Jan) shows Graeme, one of our Monday weeders, in waders immersed in an in-depth weeding experience removing a Honeysuckle infestation coming down from the top of the creek bank in Furness Park – while also collecting rubbish.

Drain Flat Sedge or Umbrella Sedge (Cyperus eragrostis)

Umbrella sedge

  • Drain Flat Sedge is a species of sedge native to the West Coast of North America as well as to parts of South America.  It is found in riparian areas (river or creek banks), roadside ditches, drains, damp grasslands, and other moist habitats.
  • Our picture shows a cluster of weeds at the southern end of the Waratah Wetlands – the weed of the month is the weed looking like an umbrella without its cover.  The seed heads turn a brown colour when ripe and its roots often have a reddish colour.

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(English) Ivy (Hedera helix)

english ivy

  • Ivy originally comes to us from England.  It is a vigorous scrambler forming a carpet on the ground and is also a climber (to 30 metres).  It can smother indigenous plants and even pull down trees with its weight – especially when heavy after rain.
  • It is very hard to eradicate – growing from seed, small pieces and stems setting roots where they touch soil.  Interestingly, seed only forms on climbing  parts and is spread by birds – making it doubly important to keep ivy from growing up your trees…

White Clover (Trifolium repens)

white clover

  • White Clover is native to Europe and central Asia and has been introduced worldwide as an animal crop.  It is a herbaceous perennial of the bean family and is an Environmental Weed in the park.
  • It is low growing, often forming mats from creeping stems, with round heads of irregular whitish flowers (not shown in the photo).  The leaves form the familiar shamrock symbol and often show a white “V” marking .

Panic Veldt grass (Ehrharta erecta)

  • Panic Veldt comes to us from Africa and is an invasive, perennial grass with both profuse and rapid seed production.  The inset in the picture shows the tell-tale ‘inflorescences’ – the botanical term used for the flowering and seed-producing part of any flowering plant.  As they dry out, they become white – a good way to identify the weed from good grasses.
  • It is opportunistic – quickly invading newly disturbed areas, seeds all year round and quite possibly rates as the Number One weed in the park.  It usually grows 30-50 cm high and older plants can spread a metre or more.  Unfortunately, it tends to out-compete indigenous ground covers in most soil conditions.
  • The good news is that its roots are weak – so the pest is quite easily pulled out.

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Cape Ivy (Delairea odorata)

cape ivy

  • Cape Ivy comes to us from South Africa.  Its leaves resemble those of English Ivy.  It is a light green creeper with green and sometimes purple stems and has a strong limey smell when crushed.
  • The plant will smother shrubs and trees and will also cover the ground intensively, preventing good seeds from germinating and growing.  The plant has been grown as an indoor ornamental and is now a significant pest here and in places like New Zealand and California.
  • It has clusters of bright yellow flowers in Autumn/Winter–making it more conspicuous and easier to find.  It drops seed in Spring – making the winter months a good time to try to get rid of it.   It will also propagate from stem pieces that are left in contact with moist soil or left behind when stems break while being collected.  Our Friends know never to dump garden refuse in the park – this is one way it spreads.

 Wandering Trad / Creeper (Tradescantia albiflora or T. fluminensis)

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  • Wandering Trad comes to us from South America and is an environmental weed which has invaded several areas within the park – and also many home gardens.
  • It tends to proliferate along waterways as broken plant fragments readily take root in moist soil.  It also spreads easily from garden waste dumped (illegally) in the park..
  • Our Maintenance Team is justifiably proud of the success it has been having with this pest.  Slowly but surely, we’re getting rid of it on top of the banks and are now tackling it on the banks as well.

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angled onion

  • Angled Onion (Allium triquetrum).  It looks like a thick green grass 20-40 cm high at this time of year or like chives when very young.   On close inspection, its stems have three acute angles and has an obvious onion-like smell (hence the name).   It flowers in late winter and spring with white bell flowers.  It spreads by seed and bulb division.
  • For gardeners who use Glycosophate spray, the plant is practically immune until the flowers appear.   It’s best to simply dig it out – including the bulbs.  For the more adventurous, but don’t take our word for it, the plant is supposed to be edible!

rat tail grass

  • Parramatta Grass or Rat Tail grass (Sporobolus africanus) is a very tough and wiry tussock grass with bluish-green folded or flat leaves up to 5mm wide.  It usually grows to under 45cm high.  Flowering stems are erect with a seed head up to 18cm long.  Our photo, taken from above, shows that the branches of the seed head are very short, so that the whole head looks to be a single spike.
  • It comes to us from Africa and is a widespread weed in Australia.  In Blackburn, it is typically found growing in lawns, sports grounds and nature-strips where it is resistant to mowing.  It is flowering now.   We’ve weeded it out of our new grasses regen area in Furness Park.

Bridal Creeper (Asparagus asparagoides)

  • Bridal Creeper has become a serious environmental weed in Australia and was first introduced from South Africa in the 1850s.  bridal creeper
  • It has small, bright shiny green leaves and pendent white flowers during winter and spring.  It is a scrambler and/or climber and can reach 3 metres in length.   The picture above shows an example in Furness Park where it is commencing to compete with the good, indigenous Mountain Clematis (Clematis aristata) [darker leaves].
  • It tends to smother native vegetation upstairs and downstairs – firstly,with its thick foliage and, also with its thick underground clumps of tubers which restrict the roots of indigenous species.

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Flickweed (Cardamine hirsuta)

flickweed

  • Flickweed is an annual plant native to Europe and Asia.  The photo shows it beginning to reappear in the park.   Our photo shows a cluster in Furness Park north of the bridge.  It grows best in damp, recently disturbed soil – eg (ironically) following weeding.
  • These conditions are prevalent in plant nurseries and it may be introduced with nursery plants.  It gets its name from its “explosive” habit of flicking its ripe seeds when the plant is touched – so it is much better to weed out before it flowers and sets its seeds in Spring until Autumn.

Fat Hen (Chenopodium album)

fat hen

  • Fat Hen is extensively cultivated and consumed in Northern India as a food crop but is mostly considered a weed elsewhere.  In the park, it is a robust and competitive weed which often swamps indigenous plants nearby.
  • Our picture shows a dense clump growing in the park near the Middleborough Road bridge in a hard-to-eradicate position.  It tends to grow upright at first, reaching heights of 10–150 cm, but typically falls over after flowering – being unable to support the weight of its foliage and prolific seeds unless it is supported by other plants or fencing.  As its common name suggests, its leaves and seeds are sometimes used to feed poultry.

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Cleavers (Galium aparine)

  • Cleavers are also called Goosegrass and Stickyweed.  Cleavers are prolific annual weeds having straggling stems which branch and grow along the ground to climb over other plants often tending to smother them –  attaching themselves with small hooked “sticky” hairs on their leaves and stems.
  • They flower with a small white star from spring to summer which later produces a round green/purple burr which sticks very easily to clothing and animal fur – aiding in the weed’s dispersal.  It is native to Europe, North Africa and Asia though has spread almost world-wide.

Oxalis or Soursob (Oxalis pes-caprae)

oxalis

  • Oxalis is indigenous to South Africa and is an invasive species here.  Our photo shows it trying to crowd out indigenous grasses planted in the area adjacent to 60 Main Street.
  • It has clover-like leaves and raises a yellow flower from winter to summer.  It spreads rapidly from underground bulbs which are often unwittingly left intact when the top parts of the plant are “weeded”.

Kikuyu (grass) (Pennisetum clandestinum)

kikuyu

  • Kikuyu is a tropical grass species native to East Africa (Kenya).  It has thick rhizomes and a strong network of roots, which send up new shoots easily – it also spreads via creeping stems.  It is often used on grassed areas such as parks and lawns because it is cheap, tough and stays green over summer – being quite drought-tolerant.  On the other hand, it doesn’t tolerate frost so well (being a tropical grass).
  • Its main problem in the Creeklands is that it is invasive from mown areas and can climb over good plants, smothering them and insidiously producing herbicidal toxins that attack competing plants.  Our photo shows an infestation in Kalang Park a little north and east of Kalang Oval.

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Arum Lily (Zantedeschia aethiopica)

arum lily

  • This is a garden escapee and still seen in many local gardens – even though it is allegedly toxic to stock and humans with fatalities to both recorded.
  • It likes damp land, creek banks and has come to us from South Africa. It is a perennial that forms large clumps to 1.5m high and has tuberous underground stems (rhizomes) and fleshy white roots which can go quite deep. This often makes it difficult to dig out – and treatments like glyphosate are often ineffective.  This photo from Furness Park shows how they like to grow close to the water (nestled in buttercups) in the flood zone. The inset shows the familiar flower.

Fumitory (Fumaria capreolata)

fumitory

  • Fumitory is an herbaceous annual in the poppy family and is native to Europe, west Asia and north Africa.  You may have noticed it in your garden – it comes up in late winter and spring.  It is mainly a weed of riparian areas including creek banks and  urban bushland – preferring partially shady, wetter habitats where it can form a dense ground cover and may also climb up over lower-growing vegetation smothering them.
  • It has bright light green foliage and may have either white or pink and claret flowers.  It seems to seed prolifically.  The examples above (near the Billabong) show Fumitory beginning to smother a Lomandra at left and the density of seedlings coming up through leaf litter.  The good news is that it pulls out quite easily.

Angled Onion (Allium triquetrum) 

  • No, it’s not “native snow bells” or some such – as this author is ashamed to say he thought until having had some experience with the Monday/Thursday Maintenance Team – it’s a quite invasive weed.

angled onion

  • At this time of year (late winter and spring), it is flowering with white bell flowers and has a small bulb at its base when dug up.  On close inspection, its stems have three acute angles and has an obvious onion-like smell (hence the name).   It spreads by seed and bulb division.
  • For gardeners who use Glycosophate spray, the plant is practically immune until the flowers appear.   It’s best to simply dig it out – including the bulbs.
  • For the more adventurous, but don’t take our word for it, the plant is supposed to be edible!

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 Wandering Trad / Creeper (Tradescantia albiflora or T. fluminensis)

wandering trad

  • Wandering Trad comes to us from South America and is an environmental weed which has invaded several areas within the park – and also many home gardens.
  • It tends to proliferate along waterways as broken plant fragments readily take root in moist soil.  It also spreads easily from garden waste dumped (illegally) in the park.
  • We have had some success in controlling its inexorable march up the creek banks by raking it up and rolling it onto itself (shown in the photo) – leaving it to smother itself and (hopefully) die.

Petty Spurge (Euphorbia peplus)

petty-spurge

  • Petty Spurge is also known in some places as Radium Weed, Cancer Weed and Milkweed.  Our photo shows an example in Blacks Walk (the blue flowers have dropped from a Kangaroo Apple above).  It is an annual with light green foliage growing between 5–30 cm with smooth stems. It usually pulls out easily as long as the you pull from the base of the stem.
  • It has a thick white sap which explains its last-mentioned common name (although other, unrelated plants are also called “Milkweed”).  As for the second and third common names, the plant’s sap has long been used as a traditional remedy for common skin lesions including cancers – it apparently being toxic to rapidly replicating human tissue.  Wearing gloves when weeding is always good advice – but obviously very important when dealing with weeds of this nature.  Special care should also be taken to ensure the sap does not get into one’s eyes.
  • The weed is native to Europe, North Africa, and Western Asia but has also invaded Australia, New Zealand and North America.  It is a common local garden weed which typically grows in cultivated land, gardens and other land such as our park where disturbed by weeding.

Annual Veldt Grass  (Ehrharta longiflora)

annual veldt grass

  • This is one of the infamous veldt grasses that are serious environmental weeds – being very invasive and disruptive to indigenous ecosystems.  This particular variety is an annual – very prolific, setting large amounts of seed.  Native to South Africa, it is now widespread and common particularly in coastal areas and along creek lines.  A particularly bad infestation is present to the south of the Furness bridge.

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Ixia (Ixia spp)

ixia

  • Ixia is a family (genus) sometimes called Corn Lilies – possibly, the plant shown above may be yellow ixia (Ixia dubia).   Other species have also been found in the park.  Our photo shows an example growing on the northern bank of the creek near the Laurel Grove bridge and is probably a garden escapee.  Most species seem to be native to South Africa.  When disturbed, their bulbs seem to break up into hundreds of bulblets – possibly accounting for how easily they spread.
  • Some say Ixia derives from the Greek word for bird droppings (maybe a reference to sticky sap?) – others say it comes from the ancient Greek word for the Pine Thistle – an unrelated plant in the Daisy family.

Creeping Buttercup (Ranunculus repens)

creeping buttercup

  • Creeping Buttercup is a yellow flowering plant native to Europe, Asia and northwest Africa.  It has erect flowering stems up to 50 cm high as well as prostrate running stems, which produce roots and new plants at the nodes, rather like strawberry plants.
  • It likes damp places and becomes quite dense.  The photo shows an example growing quite densely along the water’s edge in Furness Park.

Chilean Needle Grass (Nassella neesiana)

  • Chilean Needle Grass needs expertise to identify because it looks quite similar to good indigenous grasses such as the Spear Grasses and the common native tussock grass (Poa labillardieri).  Fortunately, some of our team have training in the identification of grasses.

chilean-needle-grass

  • The weed has been found on a few occasions recently and going back a few years on the hill to the south of the Furness Park bridge.  The original infestation is thought to have come in on vehicle wheels when the bridge was installed in 2010.

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Plantains – Plantago spp.

  • Plantago is a family (genus) of about 200 species of smaller, less conspicuous plants commonly called plantains or fleaworts.  We hasten to add that these plantains are not closely related to the plantain banana!
  • Ribwort plantain (Plantago lanceolata) is a common weed of cultivated or disturbed land – common in lawns. The plant is a perennial herb, with leafless, hairy flower stems (standing 10–40 cm high). The basal leaves have 3-5 strong parallel veins (“ribs”).   This photo shows an example in Kalang Park:

ribwort

  • Broadleaf or greater plantain (Plantago major) has a similar structure – this plant also is a rosette-forming perennial herb, with leafless, silky, hairy flower stems (10–40 cm):

broadleaf plantain

  • Both plants traditionally are held to have medicinal properties.

Forget-me-not (Myosotis sylvatica)

  • Forget-me-not is native to Europe and perhaps cute in a cottage garden with its dainty blue and yellow flowers – but a prolific weed in the park.  They are biennial or short-lived perennials growing to about 30cm high that self-seed to come back for many years (hence their name).  They tend to be easily pulled out – but best done before seed sets!  This example is also near the Laurel Grove bridge – near the path to Laurel Grove South:

forget me not

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Milk Thistle (Sonchus oleraceus)

milk-thistle

  • There is more than one plant called “Milk Thistle” – our enemy is botanically known as Sonchus oleraceus.  It is related to the Dandelion and originally comes to us from Europe and western Asia.
  • It is a hollow-stemmed annual which can grow to more than a metre high – commonly in disturbed soil (eg after we remove other weeds).   It is a fast grower that likes full sun and is not fussy about soil conditions.  It has yellow flowers that ripen into fluffy white seed heads – seed is then spread by wind and water.
  • In Australia generally,  it is a very common and widespread invasive species creating significant problems in agriculture.  Don’t take our word for it – but the leaves are said to be edible and the plant is also used by herbalists.  After blanching, the leaves are eaten as salad greens or cooked like spinach – perhaps a novel Christmas salad idea?