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Weed identification

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Pictures and descriptions of common Australian weeds that affect agricultural production

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Weed identification

  1. 1. Weed identification
  2. 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. 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. 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. 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. 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. 7. Bathurst Burr
  8. 8. Noogoora Burr
  9. 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. 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. 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. 12. Variegated thistle
  13. 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. 14. Sowthistle
  15. 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. 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. 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. 18. St Johns Wort
  19. 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. 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. 21. Nutgrass
  22. 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. 23. Salvinia
  24. 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. 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. 26. Patterson’s Curse
  27. 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. 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. 29. Cobblers Pegs or farmers friend
  30. 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. 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. 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.