Weed of National Significance Alligator Weed Notifiable Alternanthera philoxeroides a qu atic n t pla s

terry inkson

Origin Description Sprawling perennial, forming floating mats on water surface or in shallow water, extending many meters across the water surface. Also grows on land. Toxic for cattle. Very serious weed threat, adaptable , difficult to control. Leaves Opposite, glossy spear-shaped, 2–7cm long. Margins entire. Flowers Single, white, papery, pom pom-like on stalks that arise from the leaf axils. 1.2–1.4cm diameter. Stem Completely hollow when growing in water, reddish-brown colour on land. Roots Extensive root system to 1m deep. Dispersal Does not produce viable seed in Australia. Able to regenerate from fragments, spread by contaminated soil, earth-moving machinery, boating equipment, water. Also spread by misguided use as culinary herb. All iga Control Manual removal, foliar spray glyphosate at 10ml/L (aquatic use only). Spray with metsulfuron-methyl at 1g/10L water in terrestrial

situations only. Multiple, repeat applications are necessary. Notify tor Weed your local weeds officer for more advice.

85 cabomba Weed of National Significance Cabomba caroliniana Notifiable s pla n t atic qu a

terry inkson

Origin South America Description Cabomba is strictly aquatic and completely submerged except for its flowers and occasional floating leaves. The roots attach to the bottom of the water body and stems can be up to 10m long, but usually range up to 5m. Leaves Opposite, submerged, fan-like and feathery. Flowers Raised 1–4cm above the water surface on stalks. Milk-white, pale yellow or purplish (usually white petals with yellow centres), and appear to have 6 petals (3 of these are sepals). Flowers emerge from the water during the day and recede into the water overnight. The raised flowers are often the first visible signs of an infestation. Stem Seasonally purple to 10m long, break easily when disturbed, creating thousands of fragments, all capable of spreading and reproducing. Dispersal Has spread by seed in N.T. Usually spreads by fragments. Control Currently registered herbicides are only partially effective. Draining of a water body can be effective, particularly in smaller dams or retention ponds. Stems and leaves must be exposed until they and the substrate are completely dry. Care must be taken to ensure that Cabomba is not spread to other water bodies in the drained water. Shading can be created by floating blankets made from builders’ black plastic. This must be maintained over a period of 3 or 4 months to kill . Manual removal can be useful for small infestations or as a follow-up method to remove regrowth. It requires plants to be pulled up by the roots, either while wading through shallow water or

cab o mba by diving. 86 aquatic plants 87 a l phi gro hy Hygrophila costata Hygrophila terry inkson 10L water. Don’t spray directly onto water surface. Don’t spray spray surface. Don’t water directly onto spray g/10L Don’t water. North America, and Europe South Asia 1.5m up to growing herb, is a mat-forming Hygrophila high in lakes of freshwater the margins around mats forming water, shallow and watercourses. 18cmOpposite, long and 3cm Hairy midrib. wide with prominent underneath. are stems lower branched, erect and rarely 4-angled, are Upper stems purplish colour. to red a have may Stems nodes. at and root prostrate year. all whorls in in leaf axils, flowers Inconspicuous white 7mm about fruit capsules are The spindle-shaped long, and inconspicuous. Seeds are pale brown, flattened, round, about 0.3mmround, flattened, pale brown, Seeds are wide and sticky become when wet. stickyThe seed seed. water-dispersed and by fragments by Spreads and humans. watercraft machinery, wildlife, to also adhere may nodes when in contact from new growth sprout stems Spreading with soil. care Take infestations. isolated small, for Mechanical removal or hand the plant fragmenting appropriately; dispose of the material avoid to Prevent start could that behind pieces new infestations. and leaving with glyphosate spray Foliar risk of spread. reduce to access livestock 10mat also be used may use only). Metsulfuron-methyl l/L (aquatic at 1 pollution. water avoid than 3 times/yr, more rigin eed tems Description Leaves S Flowers Fruit S O Dispersal Control Hymenachne Weed of National Significance Hymenachne amplexicaulis Noxious Weed Class 1 s pla n t atic qu a

www.northcoastweeds.org.au

Origin South and Description Hymenachne is a semi-aquatic perennial erect grass that can grow in water up to 2m deep. It prefers swampy situations such as riverbanks and seasonally flooded areas. Leaves Leaf blades are 20–35cm long and 2–3cm wide. A distinctive characteristic of Hymenachne is that the base of the leaf blade clasps around the stem. Stems Hairless, up to 1.6m tall and containing a white pith. Submerged stems quickly produce roots from nodes. Flowers The flower-heads are spike-like and cylindrical, about 8mm wide and up to 40cm long. The plant flowers in summer and autumn. Dispersal Reproduces by seed, broken stem fragments and stolons. A large number of viable seeds are produced and require contact with waterlogged or moist soil for at least 48 hours before germination can occur. Germination can occur all year round. Stolons run along the ground and produce roots at each node, forming a new plant. Seeds and broken fragments of plant can be carried to new locations by floodwater and will take root in moist soil. It thrives in nutrient- rich water. Also dispersed in mud attached to waterbirds or in contaminated stock feed. Control Manual or spraying with glyphosate at 10ml/L, max. of four times per year. hne m en ac y H 88 aquatic plants Kidney leaf – mud plantain 89 n ai ant l p mud – Heteranthera reniformis Heteranthera ian turnbull dney le af dney Ki North America, and Europe South Asia in shallow grows that plant is an aquatic – Mud-Plantain Kidney Leaf usually less than 20cm forms water, – Mud-Plantain Kidney Leaf deep. 10–30cm usually emerge that dense mats surface. the water above but along the stems, arranged alternately are majorityThe of leaves bright The rosettes). (i.e. clusters into grouped occasionally some are borne on stalks 2–13cm are and glossy leaves green long and are kidney-shaped (1–4cm long and 1–5cm across). The underwater stems produce roots at their joints, particularly their joints, at roots underwater produce The stems usually while other stems contact soil, with into they come where surface. the water across spread 1–5cm in short arranged racemes) are (i.e. clusters flowers The long Each cluster structures. small sheath-like two from emerge that hours three approximately which bloom 2–10 small flowers, contains or pale white delicate The after early sunrise afternoon. and wilt by six petals (3–6.5mm have blue flowers long), with one of the petals markings or greenish its base. at yellow having winged seeds less 8–14 tiny fruit is a small capsule containing The than 1mm long. Seeds and plant as vegetatively. seed as well by Reproduces to attached becomes also be dispersed in mud that may fragments animals and vehicles. Mechanical or hand removal. control. for registered No herbicides are and remove fragmenting appropriately;Dispose of the material avoid partsall plant site. from rigin tems O Description Leaves S Flowers Fruit Dispersal Control parrots feather Myriophyllum aquaticum s pla n t atic qu a

terry inkson

Origin South America Description Submerged to emergent perennial herb. Can be floating or attached. Grows very well in nutrient rich waters, forming dense stands that impede water flow. Leaves All leaves in whorls, hairless with blade of submerged leaves to 4cm long, emergent leaves 2.5–3.5cm long, 0.5–0.8cm wide, crowded towards tip. Emergent leaves blue-green, in whorls of 4–6; leaves toothed with 18–36 teeth. Stems Stems spreading and erect, hairless, to 5m long and to 5mm wide, rooting at lower nodes. Flowers Male and female flowers produced on separate plants. Only female plants found in Australia. Flowers grow in leaf axils, have 4 triangular white sepals, 0.4–0.5mm long; petals absent. Fruit No fruit produced in Australia. Dispersal By stem fragments.

ther Control Physical removal. Draining and drying where possible. No herbicide registered for control. f e a s rrot pa 90 aquatic plants Salvinia 91 nia vi l Sa Salvinia molesta GA’s pia dollmann orthL NSW Coast in N 3 Class South America forms with multi- dense mats fern that floating free Perennial 5–30cm Individual are plants stems. horizontal branched long and bodies. water still or slow-moving invade heart to oval hairy shaped with green, light surfaceOpposite, waxy in complex hairs about 1mmcovered and flat are Leaves long. as small as 10mm 5mm. by act like modified leaves submerged The of short and consist hairyroots brown stalks ending in hairy filaments 50cm.up to stages: distinct as three Occurs growth leaves. oval flat, small, Primary plants, – isolated start midrib. at Secondary fold to – Leaves midrib. at folded leaves plants, – Crowded Tertiary No flowers. No fertile spores. and human activity (boating, Floodwater fragments. Disperses by dumping). fishing, success control Biological removal. Difficult.manual Mechanical and (Cyrtobagous salviniae) Weevil Salvinia The the state. varies across and Richmond river spectacular in the Clarence results has produced during spring conditions and summer in nutrient rich water systems (warm weather).

oxious Weed Weed oxious rigin Description Leaves Flowers Fruit Dispersal Control O

N ational Significance ational of N Weed Water Hyacinth Noxious Weed Class 3 & 4 Eichhornia crassipes in North Coast LGA’s s pla n t atic qu a

terry inkson

Origin South America Description Free-floating fleshy perennial water weed to 65cm tall, forming dense rafts of vegetation across still or slow-moving water bodies. Leaves Glossy bright green, can be tinged a rusty yellow on the edges. Up to 60cm long (including the petiole), narrow and erect in dense infestations. Leaves are thick stemmed, circular and up to 30cm in diameter in open water. The stems may be 50cm long and contain air, which enable the plant to float. Stems Two types of stems: Erect stems up to 60cm long, with flowers and horizontal vegetative stems (stolons) 10cm long, which produce new daughter plants. Flowers On upright spike, pale blue/lavender with a yellow and purple centre, 4 to 7cm across in showy clusters. Flowers spring–summer. Seed Ovate to oblong, ribbed to 1mm long. May remain viable for up to 20 years. Roots Fibrous and featherlike. In deep water trailing below the plant up to 1m long. In shallow water the roots may take hold in the substrate of mud or sediment. Dispersal Reproduces by seed and horizontal stems (stolons). Most rapid dispersal happens by stolons that grow into daughter plants. Water

nth aci flow and human activity disperse the infestation. y Control Manual removal for early stage of infestation. Foliar spray for large infestations with glyphosate (aquatic use only) at 10ml/L. ter H ter

a Prevent spread after flooding by mechanical removal while plant

W matter is on land. 92 aquatic plants water lettuce 93 ter lettuter ce Pistia stratiotes Pistia wa george wisemantel george GA’s terry inkson SW L NSW all 1 in Class Asia, Africa, equatorial America, possibly native in N.T. America, possibly native equatorial Africa, Asia, 20cm herb to aquatic Perennial with feathery roots. level water above veryLooks an open head of lettuce. much like They wedge-shaped ribbed, a rosette. are and form leaves green Pale the small due to appearance a velvety and have touch spongy to are 15cm to them. Leaves cover thick hairs that 8cm long and to wide. leaves. on small stalks hidden amongst whitish-green, Inconspicuous, at 5–10mm green berry, are fruit is a greenish The Fruit in diameter. about colour and are to a brown first then mature 2mm long. Four to fifteen oblong shaped seeds occur in each berry. in each berry. fifteen oblong shaped seeds occur to Four 80cm up to feathery number of unbranched roots A large long are of the plant. the leaves beneath submersed in water a and each produce stolons, produce Plants By seed and fragments. moved are plants and mature seedlings Seeds, the end. at new plant and wind. water by lettuce Water for small infestations. is effective removal Physical and can be removed cannot survive long out of the water plants for rope. either raking the bank with an encircling by pulled to or being dry to down. must be allowed out and break plants removed, Once 10m use only) at (aquatic glyphosate spray Foliar l/L.

otifiable oxious Weed Weed oxious rigin eed O Description Leaves Flowers Fruit S Roots Dispersal Control

N N