australian water weeds

7/29/2019 Australian Water Weeds

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Recognising

Water Weeds P L A N T I D E N T I F I C A T I O N G U I D E



Recognising Water Weeds

Plant Identifcation Guide Aquatic Weeds Early Detection Project

Compiled by Jessica Grantley, Fiona McPherson and Andrew Petroeschevsky,

Edited by Matthew Stevens and Elissa van Oosterhout

Enquiries: Industry & Investment NSW, Grafton PrimaryIndustries Institute,

PMB 2, Grafton, NSW 2460.

Weeds Hotline 1800 680 244 [email protected]

© The State of New South Wales Industry & InvestmentNSW 2009

Information contained in this publication may becopied or reproduced for study, research, informationor education purposes, subject to inclusion of anacknowledgement of the source. In particular, the user

of this publication agrees to include this copyright noticein any copy made.

The products described in this document are usedas examples only and the inclusion or exclusion of any product does not represent any endorsementof manufacturers or their products by Industry &Investment NSW. Industry & Investment NSW acceptsno responsibility for any information provided in thismaterial. Any questions that users have about particularproducts or services regarding the subject of thismaterial should be directed to the relevant commercialorganisation.

Dicie

This document has been prepared by the authors forIndustry & Investment NSW for and on behalf of theState of New South Wales, in good faith on the basis of available information. While the information containedin the document has been formulated with all duecare, the users of the document must obtain theirown advice and conduct their own investigations andassessments of any proposals they are considering, inthe light of their own individual circumstances. The

document is made available on the understandingthat the State of New South Wales, the author and thepublisher, their respective servants and agents acceptno responsibility for any person, acting on, or relyingon any opinion, advice, representation, statement

or information whether expressed or implied in the

document, and disclaim all liability for any loss,damage, cost or expense incurred or arising by reasonof any person using or relying on the informationcontained in the document or by reason of any error,omission, defect or misstatement (whether such error,omission, defect or misstatement is caused by or arisesfrom negligence, lack of care or otherwise). While theinformation is considered true and correct at the date of publication, changes in circumstances after the time of publication may alter the accuracy of the information.The information may change without notice and theState of New South Wales, the author and the publisher,

and their respective servants and agents are not inany way liable for the accuracy of any informationcontained in this document. The product trade namesin this publication are supplied on the understandingthat no preference between equivalent products isintended and that the inclusion of a product name doesnot imply endorsement by Industry & Investment NSWover any equivalent product from another manufacturer.Recognising that some of the information is provided bythird parties, the State of New South Wales, the authorand the publisher take no responsibility for the accuracy,

currency, reliability and correctness of any informationincluded in the document provided by third parties.

Privacy and personal inormation Act 1998

CB Alexander Agricultural College, Tocal, complies withthe Privacy and Personal Information Act 1998.

WeedED training and information resourceswere originally produced by the CooperativeResearch Centre for Australian Weed

Management. WeedED resources are nowproduced and managed by the NSW WeedsTraining Program, supported by Industry andInvestment NSW, Noxious Weed Grants and theRegistered Training Organisation Tocal College.WeedED resources are suitable for WeedsOcers, Project Ocers and Natural ResourceManagers as well as others involved inoperational, managerial or community-basedweed management. WeedED informationresources won the 2006 CRC Association Awardfor Excellence in the category of Innovation inEducation and Training and Public OutreachActivities.



Ctet

E mE rgE nt w a tE r p l a nts 5

Alligator weed Alternanthera philoxeroides 7

Arrowhead Sagittaria montevidensis 9

East Indian hygrophila Hygrophila polysperma 11

Enydra / bualo spinach Enydra fuctuans 13

Horsetail Equisetum spp. 15

Hydrocotyl Hydrocotyle ranunculoides 17

Hygrophila Hygrophila costata 19

Kidney leaf / mud plantain Heteranthera reniormis 21

Limnocharis / yellow burrhead Limnocharis fava 23

Longleaf primrose willow Ludwigia longiolia 25

Olive hymenachne Hymenachne amplexicaulis 27

Peruvian primrose Ludwigia peruviana 29

Sagittaria Sagittaria graminea ssp. platyphylla 31

Senegal tea Gymnocoronis spilanthoides 33

Smart weed / slender knotweed Persicaria decipiens 35

Water plantain Alisma plantago-aquatica 37

Water primrose Ludwigia peploides ssp. montevidensis 39

Water soldier / water aloe Stratiotes aloides 41

Comparison table of similar emergent water plants 42

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4

FE a thE ry s u b mE rgE D w a tE r p l a nts 43

Ambulia / limnophila Limnophila spp. 45

Cabomba Cabomba caroliniana 47

Eurasian water milfoil Myriophyllum spicatum 49

Hornwort Ceratophyllum demersum 51

Parrot’s feather Myriophyllum aquaticum 53

Comparison table of feathery submerged water plants 54

non-FE a thE ry s u b mE rgE D w a tE r p l a nts 55

Elodea Elodea canadensis 57

Egeria/leafy elodea/dense water

weed

Egeria densa 59

Hydrilla Hydrilla verticillata 61

Lagarosiphon Lagarosiphon major 63

Comparison table of similar non-feathery submerged water plants 64

Fl oatng w a tE r p l a nts 65

Anchored water hyacinth Eichhornia azurea 67

Azolla Azolla spp. 69

Duckweed Lemna spp., Wola spp., Spirodela spp. 71

Salvinia Salvinia molesta 73

Water caltrop Trapa spp. 75

Water hyacinth Eichhornia crassipes 77

Water lettuce Pistia stratiotes 79



E M E R G E N T W A T E R P L A N T S

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Emergetter t



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©University o Florida Center or Aquatic and Invasive Plants

Photo: NSW DPI

Photo: Bruce Auld




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aigtr eed Alternanthera philoxeroides

DescriptionSprawling emergent perennial. Forms oatingmats on water surface or grows rooted in soilat water’s edge or in shallow water, extendingmany metres across the water surface. Alsogrows on land.

leve:

■ Opposite■ Glossy, spear-shaped, 2–7 cm long

■ Smooth marginFe:

■ Single, white, papery, ball-like, 1.2–1.4 cmdiameter■ On short stalk in leaf axils (stem and leaf junction)

se:

■ Aquatic alligator weed: completely hollow■Terrestrial alligator weed: reddish-brown

Similar looking species

■ #Water primrose (Ludwigia peploides ssp.montevidensis): yellow owers, alternateglossy leaves■ #Smart weed (Persicaria decipiens): alternatehairy leaves, dark blotch in centre, small pinkor white owers on spike■ Senegal tea (Gymnocoronis spilanthoides):

irregularly toothed leaf margins, ribbed stemsthat are hollow between the joints, half-sphere-shaped (pom-pom-like) white or palepurple ower heads in clusters■ Hygrophila (Hygrophila costata): stems four-angled, whorled owers around stem and leaf

junction

■Alternanthera spp: no ower stalks

Background

Alligator weed is native to South America andwas rst discovered in Australia during the 1940sin the Hunter River, NSW. It is believed that plantfragments were accidentally introduced via ship’sballast water. Alligator weed is regarded as oneof Australia’s worst weeds due to its impact,invasiveness, capacity to spread and regenerate

from fragments, and ability to tolerate a range of control treatments.

Distribution

About 5000 hectares in the Greater Sydney andHunter regions in NSW is infested with alligatorweed. Smaller infestations are found in Vic, Qld,ACT and regional NSW.

Means of spread

Alligator weed does not produce viable seed, andspreads by fragments. Earthmoving equipment,boating equipment and water movement havebeen responsible for much of the spread, andsome infestations may have been deliberatelyplanted.

Declaration status

WoNS. Vic: S; NSW: C2(84)/C3(44); SA: 1@; WA:P1/2; Tas: D; Qld: C1; NT: A/C; ACT: C1/4

If found, report this weed to your local weedauthority.

# Denotes Australian native species.

WEED OF NATIONAL SIGNIFICANCE

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©Botanic Gardens Trust, Sydney

Photo: Graham Prichard





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DescriptionMainly emergent to 1 m tall.

leve:

■ Adult leaves: strongly arrow-shaped, to 25cm long■ Submerged juvenile leaves: strap-like

Fe:

■ 3 white petals, 2.5 cm diameter

■ 2–12 whorls of owers at apex of a leaessstem■ Whorls of male owers situated abovefemale owers

■ Summer

seed:

■ Laterally attened, 0.15–0.3 cm long withwings

Similar species

■ Sagittaria ( Sagittaria graminea ssp. platyphylla): spear-shaped leaves■ Juvenile leaves similar to Vallisneria spp.,Ottelia ovalifolia, Alisma plantago-aquatica■ #Water plantain ( Alisma plantago-aquatica):owers on long stems and leaves rounderat base

BackgroundArrowhead is native to South America and isa common weed of rice in Australia. It growsin warm-temperate, shallow, stationary orslow-moving water and can obstruct drainagechannels and compete with rice crops.

Distribution

Primarily found in rice-growing areas of south-western NSW. Has also been found in a number

of waterways in Vic.

Means of spread

Arrowhead reproduces by seed, which is spreadby water and attaches to the hooves and fur of animals.

Declaration status

NSW: C5(S); SA: 1@; WA: P1/2; Tas: D

If found, report this weed to your local weedauthority.# Denotes Australian native species.

arred Sagittaria montevidensis

NOxIOuS IN SOmE STATES

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Photo: Suzanne Hayward

Photo: NSW DPI




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DescriptionSubmerged and emergent perennial to 50 cmtall.

leve:

■ Opposite■ Spear-shaped, 0.7–8 cm long, pointed tips■ Submerged leaves: longer with small leaf stalk■ Emergent leaves: slightly rounder with no leaf stalk

■ Variable leaf colour: bright green to brown toreddish

Fe:

■ Small, 0.5–0.6 cm long, bluish-white■ In emergent leaf axils (stem and leaf junction)

se:

■ Emergent: squarish in cross section and

slightly hairy■ Submerged: round and can grow over 2 m

long

Fi:

■ Capsule 0.6–0.7 cm long, contains 15–25seeds

seed:

■ Pale brown, round and attened, 0.08 cm in

diameter

Similar looking species■ Alligator weed ( Alternanthera philoxeroides):single white ball-like ower on stalk andhollow stem■ Hygrophila (Hygrophila costata): leaves up to18 cm long

Background

East Indian hygrophila is native to South-EastAsia and is found in tropical regions of the world.It has been used in Australia as an aquariumplant. It is particularly dicult to control as itreproduces by stem fragmentation and from leaf nodes.

Distribution

Widespread in south-eastern Qld and in severallocations on the North Coast of NSW.

Means of spread

East Indian hygrophila can reproduce byfragments and from leaf nodes, which are spreadby water, and by attaching to boats and shingequipment.

Declaration status

NSW: C1(S); WA: Unass.


Et di ygriHygrophila polysperma

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©Botanic Gardens Trust, Sydney Photo: Graham Prichard





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DescriptionEmergent perennial herb.

leve:

■ Opposite■ Spear-shaped, 2.5–8 cm long, 0.6–2 cm wide■ Serrated margin

Fe:

■ Yellowish owers in leaf axils (stem and leaf

junction)■ Summer


■ Alligator weed ( Alternanthera philoxeroides):single white ball-like ower on stalk andhollow stem

BackgroundEnydra is an Australian native aquatic plant thatcan be easily confused with alligator weed. It isnot considered a weed, although it sometimesforms large oating mats of tangled stems thatcan be carried downstream during oods.

Distribution

Enydra grows in swamps and aquatic areas incoastal regions of Qld and NSW north from Port

Hacking. It is common around the Newcastlearea, causing some minor problems in theWilliams River and minor creeks.

Means of spread

Enydra reproduces by seed.

Declaration status

Not declared a weed in Australia.

Do not report this plant.


Eydr / buf icEnydra uctuans



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Photo: Jennier Anderson Photo: Larry Allain




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DescriptionEmergent, non-woody, non-owering perennialherb.

leve:

■ Short, tooth-like; circle the stem in rings of 6–18

se d :

■ Erect, segmented stems or shoots

■ Break easily at joints■ Hard and rough owing to silica in the tissues

Two kinds of shoots:

■ – green, branched, hollow shoots■ – pale brown, unbranched shoots bearingfruiting cones 1–4 cm long; die back each year

Background

Horsetail is native to most areas of the Northern

Hemisphere. It is a highly invasive plant thatreduces crop yields and is toxic to livestock.Twelve of the 30 horsetail species are consideredweeds. The common horsetail (Equisetumarvense) and scouring rush horsetail (E. hyemale)are of most concern in Australia.

DistributionHorsetail occurs in cold- to warm-temperateregions. It grows well in damp areas withdisturbed soils and can tolerate low nutrientlevels. Horsetail has spread to New Zealand,Madagascar and parts of South America. Thecommon horsetail (E. arvense) is a weed in areasof Australia where annual rainfall is around 1400mm.

Means of spreadHorsetail spreads almost entirely by rhizomes.Small pieces of tuber or rhizome broken from theplant can grow into new plants. It also producesmillions of tiny, dust-like spores that requiremoist conditions to successfully germinate. Somehorsetail species have been found oered forsale.

Declaration status

National Alert List plant. Vic: S; NSW: C1(S); SA:1@; WA: P1/2; Tas: D; Qld: C1; NT: C; ACT: C1/4


hretiEquisetum spp.

NATIONAL ALERT SPECIES

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©University o Florida Center or Aquatic and Invasive Plants Photo: Jessica Grantley

Photo: Jessica Grantley




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DescriptionEmergent perennial.

leve:

■ Floating or emergent■ Round to kidney-shaped with 3–11 deep orshallow lobes■ To 10 cm wide

Fe:

■ 0.3 cm diameter■ 5–10 on slender 2-cm stalk■ Spring to autumn

oe:

■ Almost circular fruit that breaks into segments


■ Shield pennywort (Hydrocotyle verticillata):

groups of 3 owers on a slender stalk■ Kidney leaf / mud plantain (Heterantherareniformis): rounded leaves

BackgroundHydrocotyl is native to North and South Americaand is a fast-growing plant that grows overwater or land. It was rst recorded in Australiain 1983 near Perth and quickly covered 7 km of the Canning River. It is occasionally used as anaquarium plant and is reported to have escapedfrom ornamental garden ponds.

Distribution

Hydrocotyl is currently found in coastalfreshwater streams and water storages nearPerth.

Means of spread

Spread occurs from stem fragments that produceroots at each node.

Declaration status

SA: 1@; WA: P1/2


hydrctyHydrocotyle ranunculoides


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© L. Elkan, Botanic Gardens Trust, Sydney

Photo: NSW DPI

Photo: NSW DPI




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DescriptionEmergent to 1.5 m high.

leve:

■ Opposite leaves■ To 1.8 cm long, 0.3 cm wide■ Prominent midrib■ Generally hairy lower surface

Fe:

■ Inconspicuous whitish owers■ In whorls in leaf axils (stem and leaf junction)■ Year round

se:

■ Four-angled and generally hairy


■ Alligator weed ( Alternanthera philoxeroides):

white ower on stalk, completely hollowstems■ East Indian hygrophila (Hygrophila polysperma): sprawling habit, smaller leaves(0.7–8 cm long), variable leaf colour, brightgreen to brown to reddish■ Senegal tea (Gymnocoronis spilanthoides):irregularly toothed leaf margins, ribbed stemsthat are hollow between the joints, half-sphere-shaped (pom-pom-like) white or pale

purple ower heads in clusters

■ #Smart weed (Persicaria decipiens): alternatehairy leaves■ #Water primrose (Ludwigia peploides ssp.montevidensis): yellow owers, alternateglossy leaves

Background

Hygrophila is native to the region from southernMexico to Argentina. It is an aggressive aquaticor semi-aquatic plant that forms mats of dense

growth around the margins of watercourses.It was sold as an aquarium plant and has beencollected in Australia only since the 1990s,suggesting that it is a recent naturalisation.

Distribution

Hygrophila has naturalised and became a weedin south-eastern Qld and north-eastern NSW.

Means of spread

Spreads by fragments and by water-dispersedseed. The sticky seeds may also adhere towildlife, machinery, watercraft and humans.Spreading stems sprout new roots from nodeswhen in contact with the soil.

Declaration status

NSW: C2(55); WA: Unass; Qld: C1

If found, report this weed to your local weed

authority.# Denotes Australian native species.

hygriHygrophila costata


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USDA-NRCS PLANTS Database / USDA NRCS. Wetland fora: Field oce illustrated guide to plant species. USDA Natural ResourcesConservation Service.

Photo: Ian Turnbull

Photo: Ian Turnbull




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DescriptionEmergent.

leve:

■ Floating or emergent■ Rounded■ To 10 cm wide on stems 20–50 cm tall

Fe:

■ White or pale blue

■ Spring to autumn


■ Hydrocotyl (Hydrocotyle ranunculoides): roundto kidney-shaped leaves with 3–11 shallow todeep lobes

Background

Kidney leaf is native to North, Central and South

America. It grows prolically in highly disturbed,

shallow, freshwater wetland habitats. It has beenused in Australia as an ornamental pond plant,and escaped plants have established in pondsand freshwater streams. It can form dense matsand is a serious weed of rice in Italy.

Distribution

Heteranthera is currently found in coastalfreshwater streams and ponds in south-east Qldand northern NSW.

Means of spread

Spread by stem fragments that produce roots ateach node.

Declaration status



Kidey e / mud tiHeteranthera reniormis

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©University o Florida Center or Aquatic and Invasive Plants Photo: NSW DPI

Photo: NSW DPI




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DescriptionEmergent to 1 m high. Grows in clumps.

leve:

■ Triangular eshly leaf stalks 5–75 cm long■ Broad and oval-shaped, 5–30 cm long and4–25 cm wide

Fe:

■ Small, yellow, 3 petals

■ Clusters of up to 15 at the end of a stalk■ All year round

oe:

■ Fruit: 2 cm wide, made up of many crescent-shaped segments■ A single fruit can produce about 1000 seeds■ Dark brown, horseshoe-shaped, ridged seeds,about 0.15 cm long

Background

Yellow burrhead is a native of Central Americaand the Caribbean islands. It has the potentialto become a major weed of waterways insemi-tropical and tropical areas of Australia. Itthrives in nutrient-enriched water and multipliesrapidly. In Asia it has been used as a food source,but severe infestations have forced farmers toabandon rice paddies.

DistributionSeveral small naturalised populations andindividual plants in garden ponds werediscovered in the Cairns and Townsville districtsin 2001–2002. An eradication campaignis currently under way to remove isolatedpopulations in northern Qld.

Means of spread

Yellow burrhead reproduces by both seed and

fragments. It behaves as a perennial in areas thathave year-round wet conditions and as an annualin areas that endure dry seasons. The ower stalkbends towards the water and releases the fruitonto the surface, where it splits into segments.These segments oat to new locations and breakdown to release seeds. Each plant is capable of producing 1 million seeds per year.

Declaration status

NSW: C1(S); WA: Prohib; Qld: C1; NT: C


limcri / ye burredLimnocharis ava


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DescriptionErect habit; shrub up to 2.5 m high.

leve:

■ Alternate■ To 15 cm long and 2.5 cm wide, reducing insize up the stem■ Leaves and stems hairless

Fe:

■ Solitary, in upper leaf axils (stem and leaf junction)■ Pale yellow, 4–5 petals, 0.2–0.25 cm long■ Open for 1 day■ Summer to winter

se:

■ Red, narrow, four-angled, usually branchedtowards the apex

Fi:

■ Oblong to narrow, 0.1–0.35 cm long and0.4–0.8 cm wide■ Numerous tiny seeds in several chambers


■ Ludwigia spp.■ #Water primrose (Ludwigia peploides ssp.montevidensis): hairless leaves, creeping or

oating hairless stems to 4 m long■ Peruvian primrose (Ludwigia peruviana): erecthabit, rounded hairy stems, hairy leaves,four-angled fruit

BackgroundLongleaf primrose willow is native to SouthAmerica, occurring from Brazil to Argentina. Itis considered a major weed in its native range.It was introduced to Australia as an ornamentalplant and was rst recorded as naturalised nearSydney in 1991.

Distribution

Longleaf primrose willow has a very limited

distribution in Australia. Recent infestations haveoccurred around Port Stephens and Gosford onthe Central Coast of NSW.

Means of spread

Longleaf primrose willow reproduces by seedand fragments. Seeds are extremely small (<1mm long) and are dispersed by water, wind andhuman activity.

Declaration statusNSW: C3(36); SA: 1@; WA: Prohib; Qld: C1



lge rimre iLudwigia longiolia


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©University o Florida Center or Aquatic and Invasive Plants Photo: Qld DPI&F

Photo: Qld DPI&F




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DescriptionEmergent semi-aquatic grass, 1–2.5 m tall.

leve:

■ To 50 cm long and 3 cm wide■ Base clasps around stem

Fe:

■ On a cylindrical spike to 40 cm long■ Summer and autumn

se:

■ To 1.6 m tall■ White pith


■ #Native hymenachne (Hymenachneacutigluma): no hairy stem-clasping leaf basespresent

Background

Olive hymenachne is a native of the tropics of South and Central America. It was introduced intoQld and NT as a ponded pasture species. It hasinvaded freshwater wetlands, oodplains andcrops and is considered one of Australia’s worstweeds. It forms dense infestations, displaces

native plant species, reduces biodiversity andthreatens native wetland habitat.

Distribution

Infestations have been found in tropical Qld andNT. Smaller infestations have also been foundon the North Coast of NSW. This species has thepotential to become a major weed of wetlandsand waterways in northern NSW.

Means of spread

Olive hymenachne reproduces by seed, fragmentsand stolons. A large number of seeds areproduced and require contact with moist soilfor at least 48 hours before germination canoccur. Germination can occur all year round.Stolons run along the ground and produceroots at each node, forming new plants. Brokenplant fragments can be easily transported byoodwater and will take root in moist soil.

Declaration status

WoNS. Vic: R; NSW: C1(S); SA: 11+; WA: P1/2;Tas: S; Qld: C2; NT: B/C; ACT: C4



oive ymeceHymenachne amplexicaulis


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Graham Prichard

Graham Prichard




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DescriptionTerrestrial or partially submerged erect shrub to4 m.

leve:

■ Alternate■ 4–12 cm long, 0.6–1 cm wide■ Hairy lower surface■ Winter deciduous in Sydney area

Fe:■ Erect, showy yellow owers■ 4 (rarely 5) petals, 4 sepals■ Last 1 day■ Mid-summer

se d ce

■ Hairy

Fi:

■ Four-angled capsule, 1–2.5 cm long■ 1000–3000 tiny pepper-like seeds in eachcapsule


■ Longleaf ludwigia (Ludwigia longifolia): erecthabit; red, narrow, four-angled stem; hairlessstem and leaves■ #Water primrose (Ludwigia peploides ssp.

montevidensis): hairless leaves; creeping oroating hairless stems to 4 m long

BackgroundPeruvian primrose is native to South America andwas introduced and grown at the Royal BotanicGardens Sydney in 1907. It was rst recorded asnaturalised in Australia in the Botany Wetlands in1970 and recognised as a potential weed in 1971.It forms dense stands on watercourses, obstructsow and limits access.

Distribution

Peruvian primrose grows in stationary or slow-moving water and drying-mud creek banks incoastal regions of NSW. In the Botany Wetlands,near Sydney, it has become the dominant speciesand has replaced much of the former vegetationin these shallow urban swamps.

Means of spread

Peruvian primrose reproduces by seed. In someareas the number of seeds found below a densethicket can number over 200 000 per squaremetre. The seeds are easily spread by birds. It willalso spread by fragments, and new plants mayform oating islands.

Declaration status

NSW: C3(36); SA: 1@; WA: Prohib; Qld: C1



peruvi rimreLudwigia peruviana


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USDA-NRCS PLANTS Database / Britton, N.L., and A. Brown. 1913. An illustrated fora o the northern United States, Canada and theBritish Possessions. Vol. 1: 103.






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DescriptionEmergent to 1.2 m tall.

leve:

■ Emergent: blade-like, to 28 cm long, 10 cmwide; long stalk with one main vein■ Submerged: translucent, strap-like, to 50 cmlong

Fe:

■ 3 white petals and 3 sepals■ 3 cm diameter■ In whorls on a leaess stalk■ Always below leaf height■ Mainly spring to autumn

Fi

■ A cluster consisting of attened and wingedsegments, 0.15–0.3 cm long, 1 seed in each


■ Arrowhead ( Sagittaria montevidensis): adultleaves strongly arrow-shaped■ #Water plantain ( Alisma plantago-aquatica):owers on long stems and leaves rounder atbase

BackgroundSagittaria is native to the USA and CentralAmerica. It was introduced into and cultivatedin Australia as an ornamental garden plant. Itforms dense infestations, competes with nativespecies and obstructs water ow. It grows well inenriched conditions and is becoming increasinglycommon in irrigation supply channels, drains,shallow creeks and wetlands.

DistributionSagittaria is widespread and common in northernVic, south-east Qld, south-west NSW and aroundSydney and Newcastle.

Means of spread

Spread by seed, rhizomes, tubers and oatingentire plants.


authority.Declaration status

NSW: C4(18)/C5(S); SA: 1@; WA: P1/2; Tas: D


sgittri Sagittaria graminea ssp. platyphylla


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© Botanic Gardens, Sydney

Photo: Qld DPI & F Photo: Qld DPI & F




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DescriptionEmergent, erect or sprawling, to 1.5 m tall.

leve:

■ Opposite■ Oval to spear-shaped, 0.5–20 cm long■ Dark green■ Irregularly toothed margin

Fe:

■ Half-sphere-shaped, pom-pom-like owers1.5–2 cm diameter■ White or pale purple ower heads in clustersnear top of stem■ Late spring to early autumn■ Fragrant; attract insects, especially butteries

se:

■ Ribbed stems, hollow between the joints


■ Hygrophila (Hygrophila costata): whorledowers near stem and leaf junction, angularstem■ Alligator weed ( Alternanthera philoxeroides):white ower on stalk, completely hollowstems■ #Water primrose (Ludwigia peploides ssp.montevidensis): yellow owers, alternate

glossy leaves■ #Smart weed (Persicaria decipiens): alternate

hairy leavesBackground

Senegal tea is native to tropical and subtropicalAmerica, from Mexico to Argentina. It wasintroduced into Australia and grown as anaquarium plant. It was rst recorded as growingin the Manning River near Taree, NSW, in 1980.It grows rapidly in shallow water, forming densestands and tangled mats, and is dicult to

control.

Distribution

There are several infestations in the Sydney andHunter regions in NSW, and infestations in Tas,Vic, Brisbane and Perth.

Means of spread

Senegal tea can spread by fragments andseed, although studies have shown that seed

production is low. Stem fragments developthin, brous roots at any node that is in contactwith moist soil or immersed in water. Thesefragments can be spread by water, by animals oron equipment such as boats, trailers and lawnmowers.

Declaration status

National Alert List plant. NSW: C1(S); SA: 1@; WA:P1/2; Tas: D; Qld: C1; ACT: C1/4


seeg teGymnocoronis spilanthoides

NATIONAL ALERT SPECIES

I N TRO D U

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34

© Botanic Gardens Trust, Sydney

Photo: Qld DPI & F

Photo: Fiona McPherson




35

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In Vic, call Weed Spotters: 136 186.# Denotes Australian native species.

Description

Emergent, creeping or erect, to 1 m tall.

leve:

■ Alternate■ Dark blotch in centre■ To 15 cm long■Sometimes hairy on undersurface

Fe:

■ Small pinkish owers (rarely white) on spike■ Summer


■ Alligator weed ( Alternanthera philoxeroides):opposite leaves, hollow stem, single whiteball-like ower on stalk

■ Senegal tea (Gymnocoronis spilanthoides):opposite leaves with irregularly toothedmargins, half-sphere-shaped (pom-pom-like)white to pale purple ower in clusters at theends of branches■ Persicaria spp.

BackgroundThis Australian native is generally a usefulcomponent of wetlands. In summer it can formdense mats along the banks and margins of drainage channels and can sometime impedewater ow. It often dies back in winter.

Distribution

Common on the banks of water bodies on thecoast and in inland areas of Australia.

Means of spread

Smart weed reproduces by seed and fragments.

Declaration status

This plant is not declared as a weed.



smrt eed / eder kteedPersicaria decipiens

NA TI V E



36







37

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DescriptionEmergent, erect broadleaf.

leve:

■ Emergent leaves: spear-shaped■ Rounded base■ To 25 cm long and 10 cm wide

Fe:

■ Small, white, on long stems above height of

leaves■ 3 petals■ Last for 1 day■ Summer


■ Arrowhead ( Sagittaria montevidensis): adultleaves strongly arrow-shaped■ Sagittaria ( Sagittaria graminea ssp.

platyphylla): spear-shaped leaves, narrowerand less rounded at base

BackgroundThis Australian native is generally a usefulcomponent of wetlands. In some areas it isconsidered a weed of irrigated crops, includingrice. It can sometimes impede water ow indrainage channels.

Distribution

Found on the banks of water bodies on the coastand in inland areas of Australia.

Means of spread

Reproduces by seed and fragments. Seed canoat for over a month.

Declaration status

This plant is not declared as a weed.


wter ti Alisma plantago-aquatica

NA TI V E



38


Photo: Bruce Auld





39

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Description■ Emergent, creeping or oating stems, to 4 mlong.■ Leaves:■ Alternate, to 6 cm long, 3 cm wide■ On stems to 4 m long■ Hairless

Fe:

■ Single yellow ower■ 5 petals (sometimes 4)■ Primrose-like■ Summer (generally)

oe:

■ Long, cylindrical, hairless fruit■ Rounded, hairless stems


■ Longleaf ludwigia (Ludwigia longifolia): erecthabit, red, narrow, four-angled stem, hairlessstem and leaves■ Peruvian primrose (Ludwigia peruviana): erecthabit, rounded hairy stems, hairy leaves,four-angled fruit

■ Alligator weed ( Alternanthera philoxeroides):opposite leaves, single white ball-like owerson stalks and hollow stems■ Senegal tea (Gymnocoronis spilanthoides):opposite leaves, half sphere-shaped (pom-pom-like) white or pale purple ower headsin clusters at the ends of branches, leaves withirregularly toothed margins

Background

Native to Australia, it is sometimes problematicin areas where high nutrient levels occur. Floatingstems can grow to 4 m in length and can becomea tangled mass that could get drawn intoirrigation pumps or pose a hazard to recreationalusers.

Distribution

Occurs NSW, Vic, SA and Qld.

Means of spreadReproduces by seed and fragments.

Declaration status



wter rimreLudwigia peploides ssp. montevidensis

NA TI V E



40


Photo: NSW DPI

Photo: NSW DPI

Photo: NSW DPI




41

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DescriptionSubmerged to emergent.

leve:

■ Long, narrow, slightly triangular, spiny margin■ Extend from rosette■ Brittle■ Submerged: light green, spiny margin, to 60cm long■ Emergent: dark green, to 40 cm long, 1–4 cm

wide■ On stems to 4 m long■ Hairless

Fe:

■ On short, thick stalk, 15 cm long■ Sheath contains several white owers■ 3 petals■ Foul smell

r■ Hang free in the water or loosely rooted in thesubstrate

Background

Native to Europe. It is a fast growing plant thatforms dense stands that exclude native plantsand destroy the habitat of fauna.

Distribution

■ Not currently found in Australia.■ Means of spread■ Spread by fragments and seed.

Declaration status

NSW: C1(S); SA: 1@; WA: Prohib; Qld: C1


wter dier / ter e Stratiotes aloides


I N TRO D U

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42

C o m p

a r i s o n t a b l e o f s i mi l a r e m e

r g e n t w a t e r p l a n t s

n m e

l e f

r r g e m e t

l e f

d e s c r i t i o

l e f m r g i

l e f s i z e

F o w e r

D i s t i g u i s i

g

f e t u r e

A l l i g a t o r w e e d

( A l t e r n a n t h e r a

p h i l o x e r o i d e s )

o p p o s i t e

g l o s s y s p e a r -

s h a p e d

s m o o t h

2 –7 c m

l o n g

b a l l - l i k e o n

s t a l k ; wh i t e

c o m p l e t e l y h o l l o w

s t e m ; t e r r e s t r i a l f o r m

h a s r e d d i s h - b r o w

n

r o o t s

E n y d r a / b u a l o

s p i n a c h ( E n y d r a

f l u c t u a n s )

o p p o s i t e

s p e a r - s h a p e d

s e r r a t e d

2 . 5 – 8 c m

l o n g ,2 c m

wi d e

y e l l o wi s h ; i n

l e a f a x i l s

h o l l o w s t e m ; o w

e r

h e a d i n l e a f a x i l s

H y g r o p h i l a

( H y g r o p h i l a

c o s t a t a )

o p p o s i t e

p r o mi n e n t

mi d r i b ; h a i r y

u n d e r s u r f a c e

n e l y t o o t h e d

1 . 8 c ml o n g

0 . 3 c m

wi d e

i n c o n s p i c u o u s ,

wh i t i s h

f o u r - a n g l e d s t e m

S e n e g a l t e a

( G y mn o c o r o n i s

s p i l a n t h o i d e s )

o p p o s i t e

d a r k g r e e n

i r r e g u l a r l y

t o o t h e d

0 . 5 –2 0 c m

l o n g

h a l f - s p h e r e

p o m- p o m- l i k e ;

wh i t e t o p a l e

p u r p l e

r i b b e d s t e m ,h o l l o w

b e t w e e n j o i n t s

S m a r t w e e d

( P e r s i c a r i a

d e c i p i e n s )

a l t e r n a t e

d a r k b l o t c h i n

c e n t r e

s m o o t h

1 5 c ml o n g

o n e l o n g a t e d

s p i k e ; p i n k i s h

( r a r e l y wh i t e )

o w e r o n e l o n g a t e d

s p i k e ; d a r k b l o t c h

o n l e a f

W a t e r p r i mr o s e

( L u d wi g i a

p e p l o i d e s s s p .

m o n t e v i d e n s i s )

a l t e r n a t e

h a i r l e s s

s m o o t h

6 c ml o n g , 3

c mwi d e

5 p e t a l s ;

p r i mr o s e - l i k e

y e l l o w

o a t i n g s t e m s t o

4

m ,r o u n d e d

P h o t o : B r u c e A u l d

P h o t o : G r a h a mP r i c h a r d

P h o t o : N S W D P I

P h o t o : Q l d D P I & F

P h o t o : F i o n a M c P h e r s o n

P h o t o : B r u c e A u l d



F E A T H E R Y S

U B M E R G E D W A T E

R P L A N T S

43

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Fetery ubmergedter t



44


Photo: Andrew Petroschevsky

Photo: Andrew Petroschevsky



F E A T H E R Y S


R P L A N T S

45

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DescriptionSubmerged to emergent.

leve:

■ Whorled around stem■ Emergent: dark green and broad■ Submerged: nely divided and feathery; L. sessiliflora, bright lime colour

Fe:

■ Solitary■ In leaf axils (stem and leaf junction)■ Blue, white, pink or lavender■ Small


■ Cabomba (Cabomba caroliniana): submergedpaired leaves

BackgroundLimnophila is a genus of aquatic or semi-aquaticplants consisting of about 40 species, some of which are native to Australia. Ambulia is a verypopular aquarium plant that is often confusedwith the noxious weed cabomba (Cabombacaroliniana).

Distribution

Limnophila spp. are found in Africa, Asia, Australia

and New Guinea.

Means of spread

By seed or fragments.

Declaration status

Not declared as a weed.

ambui / imiLimnophila spp.

I N TRO D U

C E D

NA TI V E



46


Photo: Qld DPI & F

Photo: Courtesy o the Department o Natural Resources,Environment and the Arts, NT



F E A T H E R Y S


R P L A N T S

47

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DescriptionSubmerged at depths to 3 m.

leve:

■ Opposite■ Submerged: fanlike and feathery■ Emergent: elongated diamond shape

Fe:

■ Emergent

■ White■ 6 petals■ 2 cm diameter■ Solitary

oe:

■ Seasonally purple stem to 10 m long■ Free-oating fragments continue to grow


■ #Hornwort (Ceratophyllum demersum): free-oating; whorled leaves■ Ambulia (Limnophila spp.): whorled leaves■ Myriophyllum spp: whorled leaves

Background

Cabomba is a native of South America and wasintroduced into Australia during the 1930s for

use as an aquarium plant. It has since becomeone of Australia’s worst weeds. It forms denseunderwater thickets which choke waterways.

Distribution

Infestations are found in NT, Vic and variouslocations on the east coast of Australia betweenCairns and Sydney. Owing to its submergedhabit, weed managers are concerned thatother infestations may exist that are yet to be

discovered. Cabomba has the potential to invadewaterways in all states and territories.

Means of spread

Spreads by fragments. In one infestation inAustralia it is reproducing by seed (Darwin River,NT). Plant fragments can be easily transportedaccidentally by boats and boat trailers. It isbelieved that many cabomba infestations are theresult of deliberate plantings by aquatic plant

enthusiasts.

Declaration status

WoNS. Vic: R; NSW: C5(S); SA: 11+; WA: P1/2; Tas:D; Qld: C2; NT: A/C; ACT: C1/4 (Cabomba spp. WA:Unass; Qld: C2; NT: A/C)



CbmbCabomba caroliniana


I N TRO D U

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48


Photo: Alison Fox

Photo: John Somerville

Photo: Ian Dodkins



F E A T H E R Y S


R P L A N T S

49

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DescriptionSubmerged.

leve:

■ Whorled

Fe:

■ On emergent ower stem■ Whorls of 4■ Male above (pink petals), female below (no

petals)


■ #Hornwort (Ceratophyllum demersum): free-oating; whorled leaves■ Ambulia (Limnophila spp.): whorled leaves■ Myriophyllum spp: whorled leaves■ Cabomba (Cabomba caroliniana): submergedopposite leaves

BackgroundNative to Europe, Asia and northern Africa.

Distribution

Eurasian water milfoil has not been reported inAustralia.

Means of spread

Spread mainly by fragments, although it canreproduce by seed.

Declaration status

NSW: C1(S); SA: 1@; WA: Prohib; Qld: C1; NT: C



Euri ter mii Myriophyllum spicatum


I N TRO D U

C E D



50

USDA-NRCS PLANTS Database / Britton, N.L., and A. Brown. 1913. An

illustrated fora o the northern United States, Canada and the BritishPossessions. Vol. 2: 75.





F E A T H E R Y S


R P L A N T S

51

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DescriptionSubmerged and unattached (rarely looselyattached).

leve:

■ Whorled and forked■ 1.4 cm long with small teeth

Fe:

■ Inconspicuous

■ In leaf axils (stem and leaf junction)

oe:

■ No true roots■ Fruit black with 3 spines


■ Cabomba (Cabomba caroliniana): submergedopposite leaves, white owers■ Parrot’s feather ( Myriophyllum aquaticum):whorled leaves

BackgroundHornwort is a native Australia water plantwhich is a food source for waterfowl andprovides shelter for small sh and other aquaticorganisms. It sometimes forms dense mats innutrient-rich water and can restrict shing,boating and swimming. Hornwort is problematicin New Zealand, where it blocks dam intakeequipment in hydroelectric lakes.

DistributionWidespread throughout NSW, Qld, WA and NT, inwater to 10 m deep.

Means of spread

Spread mainly by fragments, but can reproduceby seed.

Declaration status

WA: Prohib; Tas: D

WA and Tas: Report this plant.# Denotes Australian native species.

hrrtCeratophyllum demersum

NA TI V E



52






F E A T H E R Y S


R P L A N T S

53

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DescriptionSubmerged to emergent perennial herb.

leve:

■ Whorled■ Feather-like■ Submerged: blade up to 4 cm long■ Emergent: blue-green, toothed, 2.5–3.5 cmlong, 0.5–0.8 cm wide, crowded at tip

Fe:■ On emergent stem■ Inconspicuous■ In leaf axils (stem and leaf junction)

se:

■ Spreading, erect and hairless


■Ambulia (Limnophila spp.)■ Cabomba (Cabomba caroliniana): submergedopposite leaves■ Myriophyllum spp.

BackgroundNative to South America and widespread aroundthe world. It grows very well in nutrient-enrichedwater and forms dense stands that impede waterow.

Distribution

Common in coastal waterways along the eastcoast of Australia from Brisbane to Sydney.

Means of spreadIn Australia, parrot’s feather spreads byfragments. Male and female owers are producedon separate plants. Only female plants have beenfound in Australia, and seed is not produced here.If male plants are introduced into Australia thisspecies may become more of a problem.

Declaration status

WA: P1/2; Tas: D; ACT: C1/4

If found, report this weed to your local weedauthority

prrt’ eter Myriophyllum aquaticum


I N TRO D U

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54

C o m p

a r i s o n t a b l e o f f e a t h e r y s u

b m e r g e d w a t e r p l a n t s

n m e

l e f r r g e m e t

l e

f d e s c r i t i o

F o w e r

D i s t i g u i s i g f e t u r e s

m g e

C b o m b

C a b o m b a

c a r o l i n i a n a

o p p o s i t e

f a n

l i k e

wh i t e

s u b m e r g e d l e a v e s , e m e r g e n t

o w e r s

a m b u i

L i mn o p h i l a s p

p .

wh o r l e d

e m

e r g e n t : b r o a d ;

s u b m e r g e d : n e l y

d i v

i d e d

b l u e ,wh i t e ,

p i n k , o r

l a v e n d e r

s u b m e r g e d o r e m e r g e n t

l e a v e s

p r r o t ’ s

f e t e r

M y r i o p h y l l u m

a q u a t i c u m

wh o r l e d

t o o

t h e d m a r g i n

i n c o n s p i c u o u

s s u b m e r g e d o r e m e r g e n t

l e a v e s

h o r w o r t

C e r a t o p h y l l u m

d e m e r s u m

wh o r l e d

t o o

t h e d m a r g i n

i n c o n s p i c u o u

s f r e e - o a t i n g


P h o t o : C o u r t e s y o f t h e D e p a r t m e n t o f N

a t u r a l

R e s o u r c e s ,E n v i r o n m e n t a n d t h e A r t s ,N

T

P h o t o : A n d r e wP e t r o s c h e v s k y

P h o t o : S u z a n n e H a y w a r d



N

O N - F E A T H E R Y S U B M E R G E D W A T E R

P L A N T S

55

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n-eteryubmerged ter t



56






N


P L A N T S

57

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DescriptionSubmerged.

leve:

■ 0.5–1.5 cm long, 0.2–0.5 cm wide■ Whorls of 3 (rarely 4)■ Bend down slightly■ Bright green

Fe:

■ On white thread-like stem■ Inconspicuous■ 3 petals■ Only male owers in Australia


■ Egeria (Egeria densa): leaves in whorls of 4–5,crowded; larger owers (2 cm wide) andleaves (4 cm long)■ #Hydrilla (Hydrilla verticillata): leaves in whorlsof 3–8; larger leaves (up to 4 cm long), almoststraight, serrated, dull green■ Lagarosiphon (Lagarosiphon major): leaves inalternate spirals; curve downwards

BackgroundElodea is native to North America. It thrives intemperate zones, can withstand freezing andgrows rapidly when temperatures exceed 15 °C.Elodea does not thrive in iron-deprived waterand has a high light requirement for optimumgrowth.

Distribution

Elodea is found in slow-moving and stationary

water bodies, coastal rivers and creeks, especiallyin colder areas in NSW, Vic and Tas. It has beena major problem in constructed waterways of northern Vic and south-western NSW.

Means of spread

Spreads by fragments. Only male owers arefound in Australia. Stems readily break intopieces which are easily transported.

Declaration statusSA: 1@; WA: P1/2; Tas: D; NT: C



EdeElodea canadensis


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58



Photo: NSW DPI



N


P L A N T S

59

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Description

Submerged, up to 1.5 m long.

leve:

■ Whorls of 4–5 (rarely 3–8)■ 4 cm long■ Minutely serrated margins■ Densely clustered

Fe:

■ White, 2 cm diameter■ Emergent■ 3 petals■ Only male owers recorded in NSW


■ Elodea (Elodea canadensis): leaves in whorls

of 3; smaller owers (5 mm long) and leaves(5–15 mm long)■ #Hydrilla (Hydrilla verticillata): leaves in whorlsof 3–8; almost straight leaves, visibly serratedmargin; smaller owers (3 mm long)■ Lagarosiphon (Lagarosiphon major ): leaves inalternate spirals, curve downwards

Background

Egeria is native to South America and wasintroduced into Australia as a popular plantfor aquariums and garden ponds. It formsdense masses and can restrict water ow,reduce aquatic biodiversity and interfere withrecreational activities.

DistributionFound in shallow lakes, ponds and slow-owingstreams in NSW, Qld and Vic.

Means of spread

Spreads by fragments, which are easily attachedto boating equipment. Only male owers havebeen recorded in Australia.

Declaration status

NSW: 5; SA: 1@; WA: P1/2; Tas: D; NT: C



Egeri/ey ede/ dee ter eedEgeria densa


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N


P L A N T S

61

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DescriptionSubmerged, to 2 m long.

leve:

■ Toothed margins■ Whorls of 3–8 (on same stem)■ Almost straight leaves■ Lower surface: very ne hairs visible undermagnication

Fe:■ Summer■ Male and female owers on dierent plants■ Female: translucent white, thread-like stem,0.3 cm; 3 petals; oats to surface in an airbubble and opens■ Male: bud-like, reddish, in upper leaf axils;oats to surface in an air bubble and opens torelease pollen


■ Elodea (Elodea canadensis): leaves in whorls of 3, bent down slightly, bright green, 0.5–1.5cm long■ Egeria (Egeria densa): crowded, minutelyserrated leaves; larger ower (2 cm diameter)■ Lagarosiphon (Lagarosiphon major ): leavescurl down in alternate spirals

BackgroundHydrilla is native to Australia and usually growsas part of a balanced community, improvingwater quality and sh production. It is sometimesregarded as a weed in Australia and is consideredto be one of the most problematic water weedsin the USA.

Distribution

Hydrilla grows in slow-moving and stationary

water bodies, coastal rivers and creeks, especiallyin warmer areas in all mainland states of Australia.

Means of spread

Spreads by fragments, rhizomes and stolons.Large numbers of tubers are produced, and it canform turions (overwintering vegetative buds) inleaf axils in winter, which break o, sink to thebottom and grow in spring and summer.

Declaration status

WA: Prohib; Tas: D

If found in Tas, report this weed to your localweed authority.


hydriHydrilla verticillata

NA TI V E




62






N


P L A N T S

63

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Description:Submerged in depths to 6.5 m.

leve:

■ Alternate spirals along the stem■ 0.5–2 cm long, 0.2–0.3 cm wide■ Tapered tips curve downwards towards thestem (except in highly alkaline water)

Fe:

■ Very small■ Female ower, 3 petals■ Clear to white■ Floats

se:

■ Curved at base (J-shaped)


■ Egeria (Egeria densa): whorled leaves to 4 cmlong; owers 2 cm diameter■ Elodea (Elodea canadensis): whorled leaves■ #Hydrilla (Hydrilla verticillata): whorled,serrated, almost straight leaves


BackgroundLagarosiphon is native to South Africa and wasintroduced into Australia for the aquariumindustry. Small infestations were discoveredand eradicated in several locations in Australiain the late 1970s, and today it is not known tobe present in Australia. However, it is a majorweed in temperate zones of the world, includingNew Zealand and Europe. It can form denseunderwater thickets in lakes, dams and pondedwaterways up to depths of 6 metres.

Distribution

There are currently no naturalised infestations of Lagarosiphon in Australia.

Means of spread

Spreads by fragments, which attach to boats andboat trailers. Many infestations are often rstrecorded at boat ramps.

Declaration status

National Alert List plant. Vic: S; NSW: C1(S); SA:1@; WA: P1/2; Tas: D; Qld: C1; NT: C; ACT: C1/4


lgriLagarosiphon major


I N TRO D U

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64

C o m p

a r i s o n t a b l e o

f s i mi l a r n o n - f

e a t h e r y s u b m

e r g e d w a t e r p

l a n t s

n m

e

l e f

r r g e m e t

l e f

d

e s c r i t i o

l e f

m r g i

l e f s i z e

F o w e r

D i s t i g u i s i g

f e

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P h o t o : N S W D P I




F L O A T I N G W A T E R

P L A N T S

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Ftig tert




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DescriptionUsually rooted in substrate to depth of 10–15 m.Can be free oating.

leve:

■ Leaf stalks (petioles) are smooth; not inated■ Emergent: generally very broad ovate, 5–16cm long, 2–16 cm wide■ Submerged or in heavy shade: strap-like,

6–20 cm long, 1 cm wide

Fe:

■ White to lavender-blue■ Uppermost petal has distinct yellow spot■ Several on erect hairy stem, 8–12 cm abovewater■ 6 toothed petals, 1–3 cm long■ Summer and autumn■ Open for 1 day

oe:

■ Submerged stems smooth and branched■ Small seeds, 0.1–0.2 cm long


Water hyacinth (Eichhornia crassipes): free-oating, erect leaves; bulbous leaf stalks; lightpurple owers with dark purple to blue centrewith yellow spot; black brous roots

BackgroundAnchored water hyacinth is native to tropicalSouth America. It is closely related to one of theworld’s worst aquatic weeds, water hyacinth(Eichhornia crassipes). Anchored water hyacinthcan grow quickly and smother the surface of creeks, lakes and other water bodies.

Distribution

If introduced and allowed to spread, anchored

water hyacinth has the potential to becomea major pest in waterways in all states andterritories.

Means of spread

Reproduces by fragments and seed. Seeds canbe carried by water, in mud, on vehicles and bybirds. Coverage spreads when part of the plantbreaks away and moves downstream and startsa new infestation.

Declaration status

NSW: C1(S); WA: Prohib; Qld: C1


acred ter ycitEichhornia azurea


I N TRO D U

C E D



68


Photo: NSW DPI


Photo: NSW DPI




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DescriptionFree-oating fern, 1–2.5 cm diameter.

leve:

■ Tiny, scale-like, 2-lobed■ Lobes 0.2 cm long■ Older leaves can be red in sunlight, green inshade

se

■ Main stem with pinnate branches■ Branches longer towards base, giving planttriangular shape■ A. filiculoides: ne rootlets absent■ A. pinnata: ne rootlets present


■ Salvinia ( Salvinia molesta): primary growthstage■#Duckweed (Lemna spp. and Spirodela spp.)

BackgroundAzolla is an Australian native fern that iscommon in many waterways and is commonlyused as a decorative feature in garden ponds. Itsupports a nitrogen-xing cyanobacterium inthe fronds. This nitrogen is released when theplants decay. Azolla is often grown in paddyelds in Asia as a fertiliser. It can quickly spreadto cover open areas of water and may build up instationary water bodies, particularly if nutrientslevels are adequate.

Distribution

Azolla is found in slow moving and stationarywaterways, and at least one species is found ineach state and territory.

Means of spread

Azolla produces spores and can spread byfragments.

Declaration status




az Azolla spp.

NA TI V E



70

©University o Florida Center or Aquatic and Invasive Plants ©University o Florida Center or Aquatic and Invasive Plants

Photo: Jessica Grantley Photo: Jessica Grantley




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DescriptionTiny, free-oating plants. Dense growth appearsas green mat on surface.

Fe:

■ Tiny, white, barely visible■ Wolffia spp: < 0.1 cm■ Spirodela spp: to 1 cm


■ Salvinia ( Salvinia molesta): primary growthstage■ #Azolla ( A. filiculoides and A. pinnata): stemand branches

BackgroundDuckweeds are native to Australia and othercountries and include the smallest oweringplants on Earth. They can form a dense green maton the water surface in nutrient-rich conditions.They are an important food source for birds andaquatic animals.

Distribution

Slow-moving and stationary waterways, with a

few species found in each state and territory.

Means of spread

Duckweeds spread mainly by fragments.

Declaration status




DuckeedLemna spp., Wolfa spp., Spirodela spp.

NA TI V E



72


Photo: SuzanneHayward

Photo: NSW DPI

Photo: Qld DPI & F

Photo: Andrew Petroeschevsky




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DescriptionFree-oating fern.

leve:

■ Opposite■ Light green; oval■ Hairy surface (repels water and aids

buoyancy)■ Eggbeater-shaped hairs on upper ‘leaf’ surface

3 e:■ Primary: isolated plants; small, at, oval

leaves■ Secondary: leaves start to fold at midrib■ Tertiary: crowded plants; leaves folded at

midrib


The primary growth stage of salvinia may be

confused with:■ #Azolla ( Azolla spp.) alternate leaves■ #Duckweed (Lemna spp., Spirodela spp.)

Background

Salvinia is native to South America and it isbelieved to have been introduced into Australiaduring the 1950s as an ornamental plant forgarden ponds. It can grow rapidly, and with hightemperatures and nutrients can double its size inless than a week.

DistributionSalvinia is found along much of Australia’seast coast from Cape York to Bega, NSW. Otherinfestations are found in NT and WA. It has thepotential to spread to still and slow-movingwaterways in all states and territories.

Means of spread

Spreads by fragments. New plants form whenrhizomes break through decay or damage.

Salvinia spreads mostly through humanactivities, on boating and shing equipment, andthrough deliberate use as an ornamental plant infarm dams or by aquatic plant enthusiasts.

Declaration status

WoNS. Vic: S; NSW: C2(106)/C3(22); SA: 1@; WA:P1/2; Tas: D; Qld: C2; NT: B/C; ACT: C1/4


authority.# Denotes Australian native species.

svii Salvinia molesta





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Two species of the genus Trapa are referred to aswater caltrop: T. natans and T. bicornis.

Description

Floating rosette with a stem attached tosubstrate.

leve:

■ Submerged: nely divided, feather-like■ Floating: triangular shape, 2–3 cm long,

toothed margins, glossy upper surface, neshort hairs on lower surface; form rosetteshape

Fe:

■ Emergent■ White; 4 petals, 0.8 cm long■ Early summer

se:

■ Unbranched to 3.6–4.5 m long

Fi:

■ Woody, 3 cm wide, 4 spines (1 cm long) (T.bicorinis has 2 spines)■ Contains a single seed

r:

■ Feather-like to 8 cm

BackgroundWater caltrop is a native of warm-temperateparts of Eurasia and Africa. The seeds are cookedand eaten in China. It forms impenetrable matsacross wide areas of water. The sharp spines of the fruit are hazardous to humans and animals.

Distribution

Not yet recorded within Australia.

Means of spreadReproduces by seed. Each seed can result in10–15 plant rosettes, and each rosette produces15–20 seeds. The seeds remain viable for up to12 years. Water caltrop can spread by the rosettesbreaking away, and by fruits detaching andoating away or being transported by birds orother animals.

Declaration status

NSW: C1(S); WA: Prohib; Tas: D; Qld: C1; NT: C; (SA:1@ T. natans)


wter ctrTrapa spp.




7676


Photo: Qld DPI & F

Photo: Qld DPI & F




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DescriptionErect, free-oating, 10 cm to 1 m tall.

leve:

■ Dark green■ Thick, waxy and glossy■ Ovate to circular, to 5 cm diameter

Fe:

■ Light purple with dark purple to blue centre

with yellow spot■ Cluster on spike above the plant

oe:

■ Leaf stems (petioles) bulbous and spongy■ Black brous root system


■ Anchored water hyacinth (Eichhornia azurea):

generally rooted in mud, yellow spot onower, no bulbous leaf stem, strap-likesubmerged leaves

Background

Water hyacinth is a native of South Americaand is a major weed of waterways throughout

the world. It was rst noticed in Australia inBrisbane, Sydney and Grafton in the 1890s andwas most likely imported as an ornamentalplant. In waterways an infestation can doublein size in a few weeks, altering aquatic habitats,providing shelter for mosquitoes and resultingin large quantities of oating biomass. Thisweight moving along a waterway can threateninfrastructures, including fences and bridges.

DistributionFound in slow-moving and stationary waterwaysin all mainland states of Australia.

Means of spread

Spreads by fragments and produces vastquantities of seed. Seeds can germinate in a fewdays or remain dormant for up to 15 years. Itspopularity as an attractive garden pond plant hasincreased its spread around the country.

Declaration status

Vic: S; NSW: C2(101)/C3(17)/C4(9); SA: 1@; WA:P1/2; Tas: D; Qld: C2; NT: A/C; ACT: C4


wter ycitEichhornia crassipes

NOxIOuS IN ALL STATES



78


Photo: Brian Worboys

Photo: Brian Worboys




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DescriptionFree-oating, to 15 cm tall and 30 cm wide.

leve:

■ Overlap like a lettuce■ Thick; covered with short hairs

Fe:

■ Inconspicuous, on small stalk hidden amongstleaves


Floating mats of water lettuce can resemble:

■ Salvinia ( Salvinia molesta)■ Water hyacinth (Eichhornia crassipes)

Background

Water lettuce is thought to be native to the NT,but is introduced in Qld and NSW. It can growrapidly under tropical conditions and adequatenutrient levels to form large mats on the watersurface. It is frost sensitive and does not thrive incool waters.

DistributionFound in slow-moving waterways throughoutthe NT, Qld and northern NSW.

Means of spread

Reproduces by fragments and seed. Plantsproduce stolons, which each produce a new plantat the end. It has been a popular ornamentalplant and is sometimes found for sale.

Declaration statusNSW: C1(S); WA: P1/2; Qld: C2; NT: B/C; ACT: C1/4


wter ettucePistia stratiotes




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