Pictures and descriptions of common Australian weeds that affect agricultural production

1. Weed identification

2. Bindweed
 Description:
Summer growing, deep rooted
perennial with creeping roots.
Slender twining stems with
runners up to 1m long. Arrow
shaped leaves on slender stalks
rising from runners. Flowers are
pink or white, trumpet-like.
Problem
 Competes for moisture and
nutrients in crops pastures and
gardens.
 Grows rapidly over cereal crops
making harvest difficult.

3. Caltrop  Description:
A prostrate, hairy summer annual.
The stems are thin, wiry, up to 1
metre long from a central taproot.
The leaves are in opposite pairs,
divided into 4-7 pairs of leaflets.
Flowers have 5 yellow petals. The
fruit is a cluster of 5 burrs, straw
coloured when ripe. Each burr is
wedge shaped, 6-9mm long with 2
long sharp spines and 2 shorter
ones.
 Problem:
- Burrs injure feet of humans and
stock, cause internal injuries if
swallowed, damage tyres,
contribute to vegetable fault in
wool.
- Spreads readily in urban and
horticultural situations.
- Unpalatable. If grazed by sheep
can cause nitrite poisoning and
photo-sensitisation.

4. Mintweed
 Description
an annual grey, green herb
with 4-sided stems. Leaves
narrow oblong with blunt tip.
Produces a strong minty
odour when crushed.
Flowers pale blue, tubular, in
opposite pairs or groups of 3
or 4.
 Problems
- a weed of roadsides, crops
and pastures
- caused nitrate poisoning in
sheep and cattle

5. Pigweed
 Description
a succulent prostrate annual with
stems often reddish brown.
Leaves shiny, oblong to wedge
shaped 1-2 cm long. Flowers in
leaf axis, yellow, solitary or
clustered.
 Problem
- common weed of cultivation in
high rainfall areas
- Suspected of causing nitrate
and oxalate poisoning

6. Bathurst Burr
 Description:
An erect, summer growing annual. The
stems are branched and straw coloured.
It has leaves that are dark green with
white or pale green veins; three lance-like
lobes with the centre lobe longer. The
flowers are minute and in the joint of the
stem and leaves. The burrs are ovoid,
about 1cm long, covered with hooked
prickles; contains two seeds (one may be
dormant for years). Stems have many
groups of 3-pronged, stiff yellowish
spines at base of each leaf or branch
 Problem:
- Burrs contaminate wool.
- Spines are obnoxious.

7. Bathurst Burr

8. Noogoora Burr

9. Noogoora Burr
 Description:
Summer annuals to 2 metres in height.
Leaves grape-vine like, hairy on both
sides. Deep tap root. Stems - dark
flecks/spots.
Flowers - inconspicuous, near stem tips
Burrs - 2 to 3cm long, covered by
hooked spines, beaked
 Problem:
- Seedlings poisonous.
- Burrs irritate stock, downgrade wool.
- Burrs spread by stock, produce,
machinery.
- Burrs invade riverbanks, swamps,
flooded areas.
- Noogoora burr capable of spreading
in dry areas.

10. Galvanised Burr
 Description:
One of the native copperburrs or
bassias, forming a densely
branched shrub to 1m high. Stems
numerous wiry, tangled, densely
wooly with fine white hairs.
Leaves oval, blunt, greyish, woolly
with fine hairs. Burrs woolly,
persistent along the branches,
each bearing three spines 8 to
15mm long and two very short
spines.
 Problem:
- Unpalatable to sheep.
- Burrs can cause vegetable fault
in wool.
- Reduces the value of pastures.

11. Variegated thistle
 Description:
Annual plant 1-4m high. Leaves
shiny, large, deeply cut, light to
dark green. White vein network
gives variegated appearance.
Tipped with strong spines.
Flowers large, purple, to 120mm
diameter. Seeds numerous, with
large pappus (parachute)
 Problem
- Smothers pastures.
- Can be poisonous to livestock.

12. Variegated thistle

13. Sowthistle
 Description
an erect annual herb with
hollow stems, exuding latex
if damaged. Thin, soft dark
green leaves with
irregularly-toothed margins,
ending in small soft spines.
Flower heads yellow.
 Problems
widespread throughout
Australia

14. Sowthistle

15. Prickly Pear Description:
A succulent perennial up to 7 metres. The
stems are fleshy, jointed into pads, generally
flat, some cylindrical. (Stems contain
chlorophyll and act as leaves.) The leaves are
mostly reduced to spines surrounded by fine
hairs in clumps on the pad surface. It has
large, brightly coloured flowers on the pad
margins. The fruit is usually fleshy, edible,
ruby red to yellow.
 Problem:
- Propagates by seed or pads in contact with the
ground.
- Survives and spreads under arid conditions.
- Obnoxious spines.
- Forms dense thickets to the exclusion of
livestock and desirable species.
- When eaten by livestock, fine bristles may
cause severe irritations in the animal's
mouth.

16. Mother-of-millions
 Description
A smooth, succulent,
erect perennial herb with
pinkish to grey stems.
Leaves almost cylindrical
with purple markings and
a slight groove in the
upper surface. Flowers
yellow to salmon red,
occurring in clusters at
end of stems.
 Problem
Its toxic and has caused
cattle deaths.
Apparently toxic to humans

17. Blackberry
 Description:
Scrambling, thorny perennial
bushes. Compound leaves of 3-5
oval leaflets. Sharp, curved
spines on lower surface veins.
Flowers white/pink with 5
petals. Fruit is black. Spread by
suckers, layered stems and seeds
 Problem:
- Invades agricultural land and
native vegetation.
- Hinders access.
- Harbours vermin.

18. St Johns Wort

19. St Johns Wort
 Description
a hairless, rhizomatous
perennial herb or small shrub.
Leaves have oil glands which
appear to be preformations
when held up to the light.
Stems reddish bearing near the
top yellow flowers with 5
petals.
 Problems
Weed of pastures. It can cause
photosensitisation in stock as
well as nervous disorders and,
in humans, contact dermatitis.

20. Nutgrass
 Description
a perennial sedge with unjointed
stems triangular in cross-section.
Bright green leaves emerge at
ground level, tapering to a point.
Underground purple, spherical
tubers are found on rhizomes.
‘Nuts’ give rise to new shoots
and new rhizomes.
 Problem
- weed in more than 90 countries
- Weed of cultivation, vineyards,
lawns, orchards and market
gardens

21. Nutgrass

22. Serrated tussock
 Description:
a densely-tussocky perennial grass.
Leaves tighly rolled, rough to
touch. In winter the species has a
characteristic yellow colour.
 Problem:
Has no grazing value to sheep and is
a major problem of grazing land

23. Salvinia

24. Salvinia
 Description:
Free floating aquatic fern.
Leaves are oval. As the
leaves multiply they become
closely folded, giving the
plant a characteristic
appearance. Upper surface
of leaves covered with white
waxy hairs. Has no true
roots. Fine leaves that look
like roots hang into the
water and absorb nutrients.
 Problem:
- Capable of reproducing very
quickly.
- Blocks lakes, dams, drains and
irrigation channels.
- Decaying debris pollutes
water.

25. Patterson’s Curse
 Description
Annual herb. Hairy, dark
green, broadly oval rosette
leaves to 30cm long; the
several seeding stems grow
to 120cm in height and
develop branches with age.
Flowers develop in clusters;
they are purple, tubular, and
2-3 cm long with 5 petals. It
has a fleshy taproot with
smaller laterals.

26. Patterson’s Curse

27. Thornapple or castor oil
 Description: Annual to perennial herb to 1 m
high and 2 m wide. Leaves ovate and 6–20 cm
long. Capsule globe-shaped, 3–5 cm long.
 Distinguishing features: Distinguished by
dense, erect glandular hairs on stems; flowers
white with green veins, 12–19 cm long, stigma
well above anthers; capsule with numerous
slender spines, all nearly the same length (to 1
cm long), capsule stalk bent sharply
downwards; seeds brown, 4–5 mm long.
 Notes: Widely distributed weed of disturbed
land. A weed of summer crops. All parts of
the plant, particularly seeds, are toxic to
livestock and humans. Rank smell and bitter
taste usually deters stock from grazing plants.

28. Bladder Ketmia
 Wide leaf bladder ketmia is an erect
annual plant, five to 150 cm tall with
waxy, green leaves that are around
90 to 100 mm long and 70 to 80
mm wide. There are two types of
wide leaf bladder ketmia. Both have
cream or yellow petalled hibiscus-
like flowers, but are differentiated by
the colour found at the centre of the
flower.
One type of wide leaf bladder
ketmia has flowers with a yellow
centre
The other type of wide leaf bladder
ketmia has flowers with
crimson/red centres

29. Cobblers Pegs or farmers friend

30. Cobblers Pegs or farmers friend
Description:
 Native to Europe, Cobblers
Peg is a herb up to 2m high.
Mainly seen shorter in
coastal areas. Found in
disturbed areas exposed to
full sun..
 Yellow sometimes white
flowers, flowering all year.
 Black seeds 1cm long with
forked tip.

31. Khaki weed
 Description:
A prostrate, creeping herb. The stems
are branched, reddish purple, and
covered with short soft hairs. The tap
root is enlarged and perennial. It has
green leaves up to 5 cm long, oval
shaped, pointed tips, in unequal
opposite pairs. The flowers are in axils
of leaves and are surrounded by fine
sharply pointed burrs. The burrs are
straw-coloured and prickly.
 Problem:
- Suspected poisoning in sheep and pigs,
skin ailments in cattle.
- Obnoxious burrs in horticultural and
urban areas over summer.
- Burrs infest wool, fodder.
- Plants spread by creeping stems.
- Seed prolific and viable for years.

32. Parthenium weed
 Description:
An annual herb with a deep tap
root and an erect stem, which
becomes woody with age. Leaves
are deeply lobed, alternate, pale
green, covered with soft fine hair.
Flowers are creamy white.
 Problem:
- Can establish in over-grazed
pastures.
- Can cause dermatitis to man.
- Direct contact between skin and
plant should be avoided.
- Allergic skin reactions in livestock
have been reported.