Recognising Water Weeds

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PLANT IDENTIFICATION GUIDE Recognising Water Weeds or information whether expressed or implied in the document, and disclaim all liability for any loss, Plant Identification Guide damage, cost or expense incurred or arising by reason Aquatic Weeds Early Detection Project of any person using or relying on the information contained in the document or by reason of any error, Compiled by Jessica Grantley, Fiona McPherson and omission, defect or misstatement (whether such error, Andrew Petroeschevsky, omission, defect or misstatement is caused by or arises from negligence, lack of care or otherwise). While the Edited by Matthew Stevens and Elissa van Oosterhout information is considered true and correct at the date of publication, changes in circumstances after the time of Enquiries: Industry & Investment NSW, Grafton Primary publication may alter the accuracy of the information. The information may change without notice and the Industries Institute, State of New South Wales, the author and the publisher, PMB 2, Grafton, NSW 2460. and their respective servants and agents are not in any way liable for the accuracy of any information Weeds Hotline 1800 680 244 or contained in this document. The product trade names [email protected] in this publication are supplied on the understanding that no preference between equivalent products is © The State of New South Wales Industry & Investment intended and that the inclusion of a product name does NSW 2009 not imply endorsement by Industry & Investment NSW Information contained in this publication may be over any equivalent product from another manufacturer. copied or reproduced for study, research, information Recognising that some of the information is provided by or education purposes, subject to inclusion of an third parties, the State of New South Wales, the author acknowledgement of the source. In particular, the user and the publisher take no responsibility for the accuracy, of this publication agrees to include this copyright notice currency, reliability and correctness of any information in any copy made. included in the document provided by third parties. The products described in this document are used Privacy and personal information Act 1998 as examples only and the inclusion or exclusion of CB Alexander Agricultural College, Tocal, complies with any product does not represent any endorsement the Privacy and Personal Information Act 1998. of manufacturers or their products by Industry & Investment NSW. Industry & Investment NSW accepts no responsibility for any information provided in this material. Any questions that users have about particular WeedED training and information resources products or services regarding the subject of this were originally produced by the Cooperative material should be directed to the relevant commercial organisation. Research Centre for Australian Weed Management. WeedED resources are now Disclaimer produced and managed by the NSW Weeds This document has been prepared by the authors for Training Program, supported by Industry and Industry & Investment NSW for and on behalf of the Investment NSW, Noxious Weed Grants and the State of New South Wales, in good faith on the basis of Registered Training Organisation Tocal College. available information. While the information contained WeedED resources are suitable for Weeds in the document has been formulated with all due Officers, Project Officers and Natural Resource care, the users of the document must obtain their own advice and conduct their own investigations and Managers as well as others involved in assessments of any proposals they are considering, in operational, managerial or community-based the light of their own individual circumstances. The weed management. WeedED information document is made available on the understanding resources won the 2006 CRC Association Award that the State of New South Wales, the author and the for Excellence in the category of Innovation in publisher, their respective servants and agents accept Education and Training and Public Outreach no responsibility for any person, acting on, or relying Activities. on any opinion, advice, representation, statement Contents

Emergent water plants 5

Alligator weed Alternanthera philoxeroides 7

Arrowhead Sagittaria montevidensis 9

East Indian hygrophila Hygrophila polysperma 11

Enydra / buffalo spinach Enydra fluctuans 13

Horsetail Equisetum spp. 15

Hydrocotyl Hydrocotyle ranunculoides 17

Hygrophila Hygrophila costata 19

Kidney leaf / mud plantain Heteranthera reniformis 21

Limnocharis / yellow burrhead Limnocharis flava 23

Longleaf primrose willow Ludwigia longifolia 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

3 Feathery submerged water plants 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-feathery submerged water plants 55 Elodea Elodea canadensis 57 Egeria/leafy elodea/dense water Egeria densa 59 weed Hydrilla Hydrilla verticillata 61 Lagarosiphon Lagarosiphon major 63 Comparison table of similar non-feathery submerged water plants 64

Floating water plants 65 Anchored water hyacinth Eichhornia azurea 67 Azolla Azolla spp. 69 Duckweed Lemna spp., Wolffia spp., Spirodela spp. 71 Salvinia Salvinia molesta 73 Water caltrop Trapa spp. 75 Water hyacinth Eichhornia crassipes 77 Water lettuce Pistia stratiotes 79 4 water plants Emergent 5 EMERGENT WATER PLANTS ©University of Florida Center for Aquatic and Invasive Plants Photo: Bruce Auld

6 Photo: NSW DPI Alternanthera philoxeroides A S Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ L grows onland. many metres across thewater Also surface. at water’s edgeorinshallow water, extending mats onwater orgrows surface rooted insoil Sprawling emergent perennial. Forms floating Description ...... species Similar looking eaves: lligator weed tem: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ junction angled, whorledflowers around stem andleaf Hygrophila ( teaSenegal ( weed ( #Smart montevidensis #Water primrose (Ludwigia Terrestrial alligator weed: reddish-brown Aquatic alligator weed: completely hollow junction) stalkinleafaxils(stem andleaf short On diameter Single, white, papery, ball-like, 1.2–1.4cm Smooth margin Glossy, spear-shaped, 2–7cmlong Opposite glossy leaves purple flower headsinclusters (pom-pom-like)sphere-shaped white orpale that are hollow between thejoints, half- irregularly toothed leafmargins, ribbedstems or white flowers onspike leaves,hairy darkblotch incentre, smallpink Hygrophila Gymnocoronis ): yellow flowers, alternate Persicaria decipiens

costata

spilanthoides peploides ): stems four- ): alternate ssp. ): ■ planted. some infestations may have beendeliberately been responsible formuchofthespread, and boating equipment andwater movement have spreads by fragments. equipment, Earthmoving Alligator weed doesnotproduce viableseed, and Means ofspread ACT andregional NSW. weed. Smallerinfestations are foundin Vic, Qld, Hunter regions inNSWisinfested withalligator intheGreaterAbout 5000hectares Sydney and Distribution control treatments. from fragments, to tolerate andability arange of invasiveness, to spread capacity andregenerate of Australia’s worst weeds dueto itsimpact, ballast water. Alligator weed isregarded asone fragments were accidentally introduced viaship’s in theHunter River, NSW. Itisbelieved that plant was firstdiscovered in Australia duringthe1940s Alligator weed isnative to Americaand South Background # Denotes Australian native species. authority. If found, thisweed report to your localweed P1/2; Tas: D;Qld:C1;NT: A/C;ACT: C1/4 WoNS. Vic: S;NSW: C2(84)/C3(44);SA:1@; WA: Declaration status ■ Alternanthera WEED OF NATIONAL SIGNIFICANCE NATIONAL OF WEED spp:noflower stalks

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C E D 7 EMERGENT WATER PLANTS ©Botanic Gardens Trust, Sydney Photo: Graham Prichard

Photo: Graham Prichard 8 S Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ L Mainly emergent to 1mtall. Description montevidensis Sagittaria A ...... Similar species eaves: eeds: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ #Water plantain ( ovalifolia, AlismaOttelia plantago-aquatica Juvenile leaves similarto platyphylla ( Sagittaria wings Laterally flattened, 0.15–0.3cmlongwith Summer female flowers Whorls ofmaleflowers situated above stem 2–12 whorlsofflowers at apex ofaleafless 3 white petals, 2.5cmdiameter Submerged juvenile leaves: strap-like cm long Adult leaves: strongly arrow-shaped, to 25 at base flowers onlongstems andleaves rounder rrowhead ): spear-shapedleaves Sagittaria Alisma plantago-aquatica

graminea Vallisneria ssp. spp., ): # Denotes Australian native species. authority. If found, thisweed report to your localweed NSW: C5(S);SA:1@; WA: P1/2; Tas: D Declaration status animals. by water andattaches to thehooves andfurof Arrowhead reproduces by seed, whichisspread Means ofspread of waterways in Vic. western NSW. Hasalsobeenfoundinanumber Primarily areas foundinrice-growing ofsouth- Distribution channels andcompete withrice crops. slow-moving water drainage andcanobstruct in warm-temperate, shallow, or stationary a common weed ofrice inAustralia. Itgrows Arrowhead isnative to Americaandis South Background N o x io u s

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C E D 9 EMERGENT WATER PLANTS ©University of Florida Center for Aquatic and Invasive Plants Photo: NSW DPI

Photo: Suzanne Hayward 10 S Fruit: long S Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ L tall. Submerged andemergent perennial to 50cm Description Hygrophila polysperma East ...... eaves: tems: eeds: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ diameter Pale brown, round andflattened, 0.08cmin seeds Capsule 0.6–0.7cmlong, contains 15–25 Submerged: round andcangrow over 2m slightly hairy Emergent: and squarishincross section In emergent leafaxils(stem and leafjunction) Small, 0.5–0.6cmlong, bluish-white reddish Variable leafcolour: bright green to brown to stalk Emergent leaves: slightly rounder withnoleaf Submerged leaves: longer with small leaf stalk Spear-shaped, 0.7–8 cmlong, pointed tips Opposite I ndian hygrophila ■ ■ equipment. by water, andby attaching to boats andfishing fragments andfrom leafnodes, whichare spread East Indianhygrophila canreproduce by Means ofspread Coastlocations ofNSW. ontheNorth Widespread Qld andinseveral insouth-eastern Distribution nodes. reproduces by stem fragmentation andfrom leaf difficult toplant. control Itisparticularly asit It hasbeenusedinAustralia asanaquarium Asia andisfoundintropical regions oftheworld. East Indianhygrophila isnative to South-East Background species Similar looking authority. If found, thisweed report to your localweed NSW: C1(S); WA: Unass. Declaration status ■ ■ 18 cmlong Alligator weed ( Hygrophila ( hollow stem single white ball-like flower onstalkand Hygrophila costata Alternanthera philoxeroides N o x io u s

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EMERGENT WATER PLANTS ©Botanic Gardens Trust, Sydney Photo: Graham Prichard

Photo: Graham Prichard 12 Flowers: ■ ■ ■ ■ ■ ■ L Emergent perennial herb. Description Similar looking species Similar looking Enydra fluctuans Enydra / buffalo spinach ...... eaves: ■ ■ ■ ■ ■ ■ Alligator weed ( Summer junction) Yellowish flowers inleafaxils(stem andleaf Serrated margin Spear-shaped, 2.5–8 cmlong, 0.6–2cmwide Opposite hollow stem single white ball-like flower onstalkand Alternanthera philoxeroides ): # Denotes Australian native species. thisplant. notreport Do Not declared aweed inAustralia. Declaration status Enydra reproduces by seed. Means ofspread Williams River andminorcreeks. area, causingsomeminorproblems inthe Hacking. Itiscommon around theNewcastle fromcoastal regions Port ofQldandNSWnorth Enydra grows inswamps andaquatic areas in Distribution can becarrieddownstream duringfloods. forms large floating mats oftangledstems that not considered aweed, althoughitsometimes can beeasilyconfused withalligator weed. Itis Enydra isanAustralian native aquatic plant that Background 13

EMERGENT WATER PLANTS ©University of Florida Center for Aquatic and Invasive Plants

Photo: Jennifer Anderson Photo: Larry Allain 14 arvense Two kinds ofshoots: S 6–18 ■ ■ ■ ■ ■ ■ L herb. Emergent, non-woody, non-flowering perennial Description Equisetum spp. H ...... weeds. The common horsetail( Twelve ofthe30horsetailspeciesare considered reduces crop yieldsandistoxic to livestock. Hemisphere. Itisahighlyinvasive plant that Horsetail isnative to mostareas oftheNorthern Background are ofmostconcern inAustralia. eaves: tems andshoots: ■ ■ ■ ■ ■ ■ fruiting cones 1–4cmlong;diebackeachyear – palebrown, unbranched shootsbearing – green, branched, hollow shoots Hard andrough owing to silicainthetissues Break easilyat joints Erect, segmented stems orshoots tooth-like;Short, circle thestem inringsof orsetail ) andscouring rushhorsetail( Equisetum E. hyemale ) mm. of Australia where annualrainfall isaround 1400 authority. If found, thisweed report to your localweed 1@; WA: P1/2; Tas: D;Qld:C1;NT: C;ACT: C1/4 Listplant.National Alert Vic: S;NSW: C1(S);SA: Declaration status sale. horsetail specieshave beenfoundoffered for moist conditions to successfully germinate. Some millions oftiny, dust-like spores that require plant cangrow into newplants. Italsoproduces Small pieces oftuberorrhizome broken from the Horsetail spreads almostentirely by rhizomes. Means ofspread common horsetail( America. ofSouth Madagascar andparts The levels. Horsetail hasspread to New Zealand, disturbed soilsandcantolerate low nutrient regions. Itgrows well indampareas with Horsetail occurs incold- to warm-temperate Distribution E. arvense NATIONAL ALERT SPECIES ALERT NATIONAL ) isaweed inareas

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EMERGENT WATER PLANTS ©University of Florida Center for Aquatic and Invasive Plants Photo: Jessica Grantley

Photo: Jessica Grantley 16 O Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ L Emergent perennial. Description Hydrocotyle ranunculoides H ...... species Similar looking eaves: ther: ■ ■ ■ ■ ■ ■ ■ ■ ■ reniformis Kidney leaf/mudplantain ( ( Shield pennywort Almost circular fruit that breaks into segments Spring to autumn stalk 5–10 onslender2-cm 0.3 cmdiameter To 10cmwide shallow lobes Round to kidney-shaped with3–11deepor Floating oremergent groups of3flowers onaslenderstalk ydrocotyl ): rounded leaves Hydrocotyle verticillata Heteranthera ): authority. If found, thisweed report to your localweed SA: 1@; WA: P1/2 Declaration status roots at eachnode. Spread occurs from stem fragments that produce Means ofspread Perth. freshwater streams andwater storages near Hydrocotyl iscurrently foundincoastal Distribution from ornamental garden ponds. aquarium plant to andisreported have escaped the Canning River. Itisoccasionally usedasan in 1983nearPerth andquicklycovered 7km of water orland. Itwas first recorded in Australia and isafast-growing plant that grows over Hydrocotyl isnative America andSouth to North Background WEED OF NATIONAL SIGNIFICANCE NATIONAL OF WEED

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EMERGENT WATER PLANTS © L. Elkan, Botanic Gardens Trust, Sydney Photo: NSW DPI

Photo: NSW DPI 18 S Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ L Emergent to 1.5 mhigh. Description Hygrophila costata H ...... species Similar looking eaves: tems: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ green to brown to reddish (0.7–8 cmlong),variable leafcolour, bright Senegal teaSenegal ( East Indianhygrophila ( Alligator weed ( Four-angled andgenerally hairy Year round In whorlsinleafaxils(stem andleafjunction) Inconspicuous whitishflowers lowerGenerally surface hairy Prominent midrib To 1.8cmlong, 0.3cmwide Opposite leaves purple flower headsinclusters (pom-pom-like)sphere-shaped white orpale that are hollow between thejoints, half- irregularly toothed leafmargins, ribbedstems stems white flower completely onstalk, hollow polysperma ygrophila ): sprawling habit, smallerleaves Gymnocoronis spilanthoides Alternanthera philoxeroides Hygrophila ): ): ■ ■ when in contact withthesoil.when incontact Spreading stems sprout newroots from nodes wildlife, machinery, watercraft andhumans. seed. The stickyseedsmay alsoadhere to Spreads by fragments andby water-dispersed Means ofspread NSW. Qldandnorth-eastern in south-eastern Hygrophila hasnaturalised andbecameaweed Distribution suggesting that itisarecent naturalisation. inAustraliacollected onlysince the1990s, It was soldasanaquariumplant andhasbeen growth around themargins ofwatercourses. or semi-aquatic plant that formsmats ofdense Mexico to Argentina. Itisanaggressive aquatic Hygrophila isnative to theregion from southern Background # Denotes Australian native species. authority. If found, thisweed report to your localweed NSW: C2(55); WA: Unass;Qld:C1 Declaration status ■ ■ montevidensis #Water primrose ( weed ( #Smart glossy leaves hairy leaves hairy ): yellow flowers, alternate Persicaria decipiens N Ludwigia peploides Ludwigia peploides o x io u s

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EMERGENT WATER PLANTS USDA-NRCS PLANTS Database / USDA NRCS. Wetland flora: Field office illustrated guide to plant species. USDA Natural Resources Conservation Service. Photo: Ian Turnbull

Photo: Ian Turnbull 20 Flowers: ■ ■ ■ ■ ■ ■ L Emergent. Description Heteranthera reniformis Kidney leaf / mud plantain ...... America. Itgrows prolifically inhighlydisturbed, Kidney leafisnative Central to North, andSouth Background species Similar looking eaves: ■ ■ ■ ■ ■ ■ Hydrocotyl ( Spring to autumn White orpaleblue To 10cmwideonstems 20–50cmtall Rounded Floating oremergent deep lobes to kidney-shaped leaves with3–11shallow to Hydrocotyle ranunculoides ): round and isaseriousweed ofrice inItaly. and freshwater streams. Itcanformdensemats and escapedplants have establishedinponds used inAustralia asanornamental pondplant, shallow, freshwater wetland habitats. Ithasbeen authority. If found, thisweed report to your localweed Not declared aweed inAustralia. Declaration status each node. Spread by stem fragments that produce roots at Means ofspread NSW.and northern freshwater Qld streams andpondsinsouth-east Heteranthera iscurrently foundincoastal Distribution

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EMERGENT WATER PLANTS ©University of Florida Center for Aquatic and Invasive Plants Photo: NSW DPI

Photo: NSW DPI 22 O Flowers: ■ ■ ■ ■ ■ ■ ■ ■ L Emergent to 1m high.Grows inclumps. Description Limnocharis flava L ...... abandon rice paddies. but severe infestations have forced farmersto rapidly. InAsiaithasbeenusedasafoodsource, thrives water innutrient-enriched andmultiplies semi-tropical and tropical areas ofAustralia. It to become amajor weed ofwaterways in and theCaribbean islands. Ithasthepotential Yellow burrheadisanative ofCentral America Background eaves: ther: ■ ■ ■ ■ ■ ■ ■ ■ imnocharis / yellow burrhead about 0.15cmlong Dark brown, ridgedseeds, horseshoe-shaped, A singlefruitcanproduce about1000seeds shaped segments Fruit: 2cmwide, madeupofmany crescent- All year round Clusters ofupto 15at theendofastalk Small, yellow, 3petals 4–25 cmwide Broad andoval-shaped, 5–30cmlongand Triangular fleshlyleafstalks5–75cmlong authority. If found, thisweed report to your localweed NSW: C1(S); WA: Prohib; Qld:C1;NT: C Declaration status producing 1millionseedsperyear. down to release seeds. Each plant iscapableof These segments float to newlocations andbreak onto where thesurface, itsplitsinto segments. bends towards thewater andreleases thefruit in areas seasons. that endure dry The flower stalk have year-round wet conditions andasanannual fragments. Itbehaves asaperennial in areas that Yellow burrheadreproduces by bothseedand Means ofspread Qld. populations innorthern is currently underway to remove isolated in 2001–2002.Aneradication campaign discovered intheCairns and Townsville districts individual plants ingarden pondswere Several smallnaturalised populations and Distribution N o x io u s

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EMERGENT WATER PLANTS ©Botanic Gardens Trust, Sydney Photo: Graham Prichard

Photo: Graham Prichard 24 Fruit: towards theapex S Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ L Erect habit;shrubupto 2.5mhigh. Description Ludwigia longifolia L ...... species Similar looking eaves: tems: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ongleaf primrose willow Peruvian primrose ( montevidensis #Water primrose ( Ludwigia Numerous tiny seedsinseveral chambers 0.4–0.8 cmwide Oblong to narrow, 0.1–0.35cmlongand Red, narrow, four-angled, usuallybranched toSummer winter for1dayOpen Pale yellow, 4–5petals, 0.2–0.25cmlong junction) Solitary, inupperleafaxils(stem andleaf Leaves andstems hairless size upthestem To 15cmlongand2.5wide, reducing in Alternate floating hairlessstems to 4mlong four-angled fruit leaves,habit, stems, rounded hairy hairy spp. ): hairlessleaves, creeping or Ludwigia Ludwigia peruviana

peploides ssp. ): erect ): erect authority. If found, thisweed report to your localweed NSW: C3(36);SA:1@; WA: Prohib; Qld:C1 Declaration status human activity. mm long)andare dispersedby water, windand and fragments. are Seeds extremely small(<1 Longleaf primrose willow reproduces by seed Means ofspread the Central Coast ofNSW. occurred around Port Stephens andGosford on distribution inAustralia. Recent infestations have Longleaf primrose limited willow hasavery Distribution Sydney in1991. plant andwas first recorded asnaturalised near It was introduced to Australia asanornamental is considered amajorweed initsnative range. America, occurring from Brazil to Argentina. It Longleaf primrose willow isnative to South Background # Denotes Australian native species. N o x io u s

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EMERGENT WATER PLANTS ©University of Florida Center for Aquatic and Invasive Plants Photo: Qld DPI&F

Photo: Qld DPI&F 26 S Flowers: ■ ■ ■ ■ ■ ■ ■ L Emergent semi-aquatic grass, 1–2.5mtall. Description Hymenachne amplexicaulis O ...... weeds. Itformsdenseinfestations, displaces crops andisconsidered oneofAustralia’s worst invaded freshwater wetlands, floodplainsand Qld andNTasapondedpasture species. Ithas andCentralSouth America.Itwas introduced into Olive hymenachne isanative ofthetropics of Background species Similar looking eaves: tems: ■ ■ ■ ■ ■ ■ ■ present #Native hymenachne ( White pith To 1.6mtall andautumn Summer spike to acylindrical 40cmlong On claspsaroundBase stem To 50cmlongand3wide acutigluma live hymenachne ): no hairy stem-clasping leafbases stem-clasping ): nohairy Hymenachne threatens native wetland habitat. native plant species, reduces biodiversity and authority. If found, thisweed report to your localweed Tas: S;Qld:C2;NT: B/C;ACT: C4 WoNS. Vic: R;NSW: C1(S);SA:11+; WA: P1/2; Declaration status floodwater andwilltake root inmoistsoil. plant fragments by canbeeasilytransported roots at eachnode, formingnewplants. Broken Stolons runalongtheground andproduce occur. Germination canoccur allyear round. for at least48hoursbefore germination can produced andrequire withmoistsoil contact and stolons. Alarge numberofseedsare Olive hymenachne reproduces by seed, fragments Means ofspread NSW.and waterways innorthern potential to become amajorweed ofwetlands Coast ofNSW.on theNorth This specieshasthe NT. Smallerinfestations have alsobeenfound Infestations have beenfoundintropical Qldand Distribution # Denotes Australian native species. WEED OF NATIONAL SIGNIFICANCE NATIONAL OF WEED

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EMERGENT WATER PLANTS ©University of Florida Center for Aquatic and Invasive Plants Graham Prichard

Graham Prichard 28 Fruit: S Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ L 4 m. Terrestrial submerged shrubto erect orpartially Description Ludwigia peruviana P ...... species Similar looking eaves: tems andbranches ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ montevidensis #Water primrose ( Longleaf ludwigia( capsule 1000–3000 tiny pepper-like seedsineach Four-angled capsule, 1–2.5cmlong Hairy Mid-summer Last 1day 4 (rarely 5)petals, 4sepals Erect, yellow showy flowers Winter deciduousinSydney area lower surface Hairy 4–12 cmlong, 0.6–1cmwide Alternate floating hairlessstems to 4mlong stem andleaves habit; red, narrow, four-angledstem; hairless eruvian primrose ): hairlessleaves; creeping or Ludwigia peploides Ludwigia longifolia ssp. ): erect ): erect form floating islands. also spread by fragments, andnew plants may metre. The seedsare easilyspread by birds. Itwill thicket cannumberover 200 000persquare areas thenumberofseedsfoundbelow adense Peruvian primrose reproduces by seed. Insome Means ofspread in theseshallow urbanswamps. and hasreplaced muchoftheformervegetation near Sydney, ithasbecome thedominant species coastal regions ofNSW. IntheBotany Wetlands, moving watercreek banksin anddrying-mud Peruvian primrose grows orslow- instationary Distribution flow andlimitsaccess. It formsdensestandsonwatercourses, obstructs 1970 andrecognised asapotential weed in1971. naturalised inAustralia intheBotany Wetlands in Gardens Sydney in1907.Itwas first recorded as was introduced andgrown at theRoyal Botanic Peruvian primrose isnative to America and South Background # Denotes Australian native species. authority. If found, thisweed report to your localweed NSW: C3(36);SA:1@; WA: Prohib; Qld:C1 Declaration status N o x io u s

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EMERGENT WATER PLANTS USDA-NRCS PLANTS Database / Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. Vol. 1: 103. Photo: Graham Prichard

Photo: Graham Prichard 30 Fruit Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ L Emergent to 1.2 mtall. Description gramineaSagittaria ssp. platyphylla Sagittaria ...... species Similar looking eaves: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ #Water plantain ( Arrowhead ( segments, 0.15–0.3cmlong, 1seedineach A cluster consisting offlattened andwinged Mainly springto autumn Always below leafheight In whorlsonaleaflessstalk 3 cmdiameter 3 white petalsand3sepals long Submerged: translucent, strap-like, to 50cm wide; longstalkwithonemainvein Emergent: blade-like, to 28cmlong, 10cm base flowers onlongstems andleaves rounder at leaves strongly arrow-shaped Sagittaria montevidensisSagittaria Alisma plantago-aquatica ): adult ): # Denotes Australian native species. NSW: C4(18)/C5(S);SA:1@; WA: P1/2; Tas: D Declaration status authority. If found, thisweed report to your localweed entire plants. Spread by seed, rhizomes, tubersandfloating Means ofspread Sydney andNewcastle. Vic, Qld, south-west south-east NSWandaround is widespreadSagittaria and common in northern Distribution shallow creeks andwetlands. common inirrigation supplychannels, drains, enriched conditions andisbecoming increasingly waterspecies andobstructs flow. Itgrows well in forms denseinfestations, competes withnative in Australia asanornamental garden plant. It America. Itwas introduced into andcultivated isnativeSagittaria to theUSAandCentral Background N o x io u s

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EMERGENT WATER PLANTS © Botanic Gardens, Sydney

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

32 S Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ L Emergent, orsprawling, erect to 1.5mtall. Description Gymnocoronis spilanthoides S ...... species Similar looking eaves: tems: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ enegal tea stem flowers angular nearstem andleafjunction, #Smart weed ( #Smart montevidensis #Water primrose ( Alligator weed ( Hygrophila ( stems,Ribbed hollow between thejoints Fragrant; especiallybutterflies attractinsects, Late springto earlyautumn near top ofstem White orpalepurpleflower headsinclusters 1.5–2 cmdiameter Half-sphere-shaped, pom-pom-like flowers Irregularly toothed margin Dark green Oval to spear-shaped, 0.5–20cmlong Opposite glossy leaves stems white flower completely onstalk, hollow Hygrophila costata ): yellow flowers, alternate Persicaria decipiens Alternanthera philoxeroides Ludwigia peploides ): whorled ): alternate ssp. ): mowers. on equipment suchasboats, trailers andlawn fragments canbespread by water, by animalsor with moistsoilorimmersedinwater. These thin, fibrous roots at any nodethat isin contact islow.production Stem fragments develop seed, althoughstudies have shown that seed teaSenegal canspread by fragments and Means ofspread Vic, BrisbaneandPerth. Hunter regions inNSW, andinfestations in Tas, There are several infestations intheSydney and Distribution control. stands andtangledmats, andisdifficult to It grows rapidly inshallow water, formingdense in theManningRiver near Taree, NSW, in1980. aquarium plant. Itwas first recorded as growing introduced into Australia andgrown asan America, from Mexico to Argentina. Itwas teaSenegal isnative to tropical andsubtropical Background authority. If found, thisweed report to your localweed P1/2; Tas: D;Qld:C1;ACT: C1/4 Listplant.National NSW: Alert C1(S);SA:1@; WA: Declaration status hairy leaves hairy NATIONAL ALERT SPECIES ALERT NATIONAL

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EMERGENT WATER PLANTS © Botanic Gardens Trust, Sydney Photo: Fiona McPherson

Photo: Qld DPI & F 34 Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ L Emergent, creeping orerect, to 1mtall. Description # Denotes Australian native species. In Vic, call Weed Spotters: 136186. Persicaria decipiens S ...... species Similar looking eaves: ■ ■ ■ ■ ■ ■ ■ ■ ■ mart weed / slender knotweed Persicaria teaSenegal ( Alligator weed ( Summer Small pinkish flowers (rarely white) onspike onundersurface hairy Sometimes To 15cmlong Dark blotch incentre Alternate ball-like flower onstalk opposite leaves, hollow stem, singlewhite ends ofbranches white to palepurpleflower inclusters at the margins, half-sphere-shaped(pom-pom-like) opposite leaves withirregularly toothed spp. Gymnocoronis spilanthoides Alternanthera philoxeroides ): ): # Denotes Australian native species. thisplant. notreport Do This plant isnotdeclared asaweed. Declaration status weed reproducesSmart by seedandfragments. Means ofspread coast andininlandareas ofAustralia. Common onthebanksofwater bodiesonthe Distribution water flow. Itoften diesbackinwinter. drainage channelsandcansometimeimpede dense mats alongthebanksandmargins of component ofwetlands. Insummeritcanform This Australian native isgenerally auseful Background

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EMERGENT WATER PLANTS Photo: Graham Prichard

©Botanic Gardens Trust, Sydney

36 Photo: Graham Prichard Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ L Emergent, broadleaf. erect Description plantago-aquatica Alisma W ...... species Similar looking eaves: ■ ■ ■ ■ ■ ■ ■ ■ ■ and lessrounded at base platyphylla ( Sagittaria Arrowhead ( Summer Last for1day 3 petals leaves Small, white, onlongstems above height of To 25cmlongand10wide Rounded base Emergent leaves: spear-shaped leaves strongly arrow-shaped ater plantain ): spear-shapedleaves, narrower Sagittaria graminea Sagittaria Sagittaria montevidensisSagittaria ssp. ): adult Do not report thisplant. notreport Do This plant isnotdeclared asaweed. Declaration status float for over amonth. Reproduces by seedandfragments. can Seed Means ofspread and ininlandareas ofAustralia. Found onthebanksofwater bodiesonthecoast Distribution drainage channels. rice. Itcansometimesimpedewater flow in considered aweed ofirrigated crops, including component ofwetlands. Insomeareas itis This Australian native isgenerally auseful Background

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EMERGENT WATER PLANTS © Botanic Gardens Trust, Sydney Photo: Suzanne Hayward

Photo: Bruce Auld 38 O Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Description Ludwigia peploidesssp. montevidensis W ...... species Similar looking ther: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Peruvian primrose ( Longleaf ludwigia( Rounded, hairlessstems Long, hairlessfruit cylindrical, (generally)Summer Primrose-like 5 petals(sometimes4) Single yellow flower Hairless stemsOn to 4mlong Alternate, to 6cmlong, 3cmwide Leaves: long. Emergent, creeping orfloating stems, to 4m four-angled fruit leaves,habit, stems, rounded hairy hairy stem andleaves habit, red, narrow, four-angledstem, hairless ater primrose Ludwigia longifolia Ludwigia peruviana ): erect ): erect ): erect ): erect ■ ■ Do not report thisplant. notreport Do Not declared aweed inAustralia. Declaration status Reproduces by seedandfragments. Means ofspread NSW,Occurs Vic, SAandQld. Distribution users. irrigation pumpsorposeahazard to recreational a tangledmassthat could getdrawn into stems cangrow to 4minlengthandcanbecome in areas where highnutrient levels occur. Floating Native to Australia, itissometimesproblematic Background ■ ■ Alligator weed ( Senegal teaSenegal ( on stalksandhollow stems opposite leaves, singlewhite ball-like flowers irregularly toothed margins in clusters at theendsofbranches, leaves with pom-like) white orpalepurpleflower heads opposite leaves, (pom- halfsphere-shaped Gymnocoronis spilanthoides Alternanthera philoxeroides

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EMERGENT WATER PLANTS Photo: NSW DPI

©University of Florida Center for Aquatic and Invasive Plants Photo: NSW DPI

Photo: NSW DPI 40 Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ L Submerged to emergent. Description Stratiotes aloides W ...... eaves: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Foul smell 3 petals Sheath contains several white flowers 15cmlong thickstalk, short, On Hairless stemsOn to 4mlong wide Emergent: darkgreen, to 40cmlong, 1–4cm cm long Submerged: light green, spiny margin, to 60 Brittle fromExtend rosette Long, narrow, slightly triangular, spiny margin ater soldier / water aloe Roots ■ ■ ■ ■ authority. If found, thisweed report to your localweed NSW: C1(S);SA:1@; WA: Prohib; Qld:C1 Declaration status Distribution and destroy thehabitat offauna. forms densestandsthat exclude native plants Native to Europe. Itisafastgrowing plant that Background ■ ■ ■ ■ Spread by fragments andseed. Means ofspread Not currently foundinAustralia. substrate Hang free inthewater orlooselyrooted inthe N o x io u s

so m

IN e S T

tates

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EMERGENT WATER PLANTS Comparison table of similar emergent water plants ( Hygrophila ( weed Smart ( Water primrose spinach ( Enydra / buffalo ( teaSenegal montevidensis peploides decipiens spilanthoides costata philoxeroides fluctuans ( Alligator weed Ludwigia Ludwigia Persicaria Gymnocoronis Hygrophila Alternanthera N ame ) ) ) Enydra ssp. ) ) ) arrangement opposite opposite alternate alternate opposite opposite L eaf spear-shaped dark green hairless centre dark blotch in shaped glossy spear- undersurface midrib; hairy prominent description L eaf serrated toothed irregularly smooth smooth smooth finely toothed L eaf margin wide long, 2 cm 2.5–8 cm long 0.5–20 cm cm wide 6 cm long, 3 15 cm long long 2–7 cm wide 0.3 cm 1.8 cm long L eaf size leaf axils yellowish; in purple white to pale pom-pom-like; half-sphere yellow primrose-like 5 petals; (rarely white) spike; pinkish on elongated stalk; white ball-like on whitish inconspicuous, Flower head in leaf axils hollow stem; flower between joints ribbed stem, hollow m, rounded floating stems to 4 on leaf spike; dark blotch flower on elongated roots has reddish-brown stem; terrestrial form completely hollow four-angled stem Distinguishing Distinguishing feature Photo: Bruce Auld Photo: Fiona McPherson Photo: DPI & F Qld Photo: NSW DPI Photo: Graham Prichard Photo: Bruce Auld

42 ...... Feathery submerged water plants 43

FEATHERY SUBMERGED WATER PLANTS ©University of Florida Center for Aquatic and Invasive Plants Photo: Andrew Petroschevsky

Photo: Andrew Petroschevsky 44 Flowers: ■ ■ ■ ■ ■ ■ ■ ■ L Submerged to emergent. Description Limnophila spp. A ...... species Similar looking eaves: ■ ■ ■ ■ ■ ■ ■ ■ paired leaves Cabomba ( Small Blue, white, pinkorlavender In leafaxils(stem andleafjunction) Solitary sessiliflora L. Submerged: finelydividedandfeathery; Emergent: darkgreen andbroad Whorled around stem mbulia / limnophila , bright limecolour Cabomba caroliniana ): submerged caroliniana Not declared asaweed. Declaration status By seedorfragments. Means ofspread Limnophila Distribution Limnophila Background with thenoxious weed cabomba ( popular aquariumplant that isoften confused which are native to Australia. Ambuliaisavery plants consisting ofabout40species, someof and New Guinea. ). isagenusofaquatic orsemi-aquatic spp. are foundinAfrica, Asia,Australia

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FEATHERY SUBMERGED WATER PLANTS Photo: Courtesy of the Department of Natural Resources, ©University of Florida Center for Aquatic and Invasive Plants Environment and the Arts, NT

Photo: Qld DPI & F 46 O Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ L Submerged at depthsto 3m. Description Cabomba caroliniana Cabomba ...... introduced into Australia duringthe1930sfor Cabomba isanative Americaandwas ofSouth Background species Similar looking eaves: ther: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ floating; whorledleaves Myriophyllum Ambulia ( #Hornwort ( Free-floating fragments continue to grow purplestemSeasonally to 10mlong Solitary 2 cmdiameter 6 petals White Emergent Emergent: elongated diamondshape Submerged: fanlike andfeathery Opposite Limnophila Ceratophyllum demersum spp:whorledleaves spp.): whorledleaves ): free- underwater thickets whichchoke waterways. one ofAustralia’s worst weeds. Itformsdense use asanaquariumplant. Ithassince become authority. If found, thisweed report to your localweed Unass; Qld:C2;NT: A/C) D; Qld:C2;NT: A/C;ACT: C1/4(Cabomba spp. WA: WoNS. Vic: R;NSW: C5(S);SA:11+; WA: P1/2; Tas: Declaration status enthusiasts. result ofdeliberate plantings by aquatic plant believed that many cabombainfestations are the accidentally by boats andboat trailers. Itis Plant fragments canbeeasilytransported NT). Australia itisreproducing River, by seed(Darwin Spreads by fragments. Inoneinfestation in Means ofspread waterways inallstates andterritories. discovered. Cabomba hasthepotential to invade other infestations may exist that are yet to be habit, weed managersare concerned that Cairns andSydney. to itssubmerged Owing locations ontheeastcoast ofAustralia between Infestations are foundinNT, Vic andvarious Distribution # Denotes Australian native species. WEED OF NATIONAL SIGNIFICANCE NATIONAL OF WEED

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FEATHERY SUBMERGED WATER PLANTS Photo: John Somerville

©University of Florida Center for Aquatic and Invasive Plants Photo: Ian Dodkins

Photo: Alison Fox 48 Flowers: ■ ■ ■ ■ ■ ■ ■ ■ L Submerged. Description Myriophyllum spicatum Eurasian water milfoil ...... species Similar looking eaves: ■ ■ ■ ■ ■ ■ ■ ■ opposite leaves floating; whorledleaves Cabomba ( Myriophyllum Ambulia ( #Hornwort ( petals) Male above (pinkpetals),femalebelow (no Whorls of4 emergentOn flower stem Whorled Limnophila Cabomba caroliniana Ceratophyllum demersum spp:whorledleaves spp.): whorledleaves ): submerged ): free- # Denotes Australian native species. authority. If found, thisweed report to your localweed NSW: C1(S);SA:1@; WA: Prohib; Qld:C1;NT: C Declaration status reproduce by seed. Spread mainlyby fragments, althoughitcan Means ofspread Australia. Eurasian water in milfoilhasnotbeenreported Distribution Native to Europe, Africa. Asiaandnorthern Background NO X IO U S IN SO IN S M E STATES E IN T

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FEATHERY SUBMERGED WATER PLANTS USDA-NRCS PLANTS Database / Britton, N.L., and A. Brown. 1913. An illustrated flora of the northern United States, Canada and the British Possessions. Vol. 2: 75. Photo: Graham Prichard

Photo: Graham Prichard 50 O Flowers: ■ ■ ■ ■ ■ ■ ■ ■ L attached). Submerged andunattached (rarely loosely Description Ceratophyllum demersum H ...... species Similar looking eaves: ther: ■ ■ ■ ■ ■ ■ ■ ■ opposite leaves, white flowers Parrot’s feather ( Cabomba ( Fruit blackwith3spines No trueroots In leafaxils(stem andleafjunction) Inconspicuous 1.4 cmlongwithsmallteeth Whorled andforked whorled leaves ornwort Cabomba caroliniana Myriophyllum aquaticum ): submerged ): # Denotes Australian native species. WA and Tas: thisplant. Report WA: Prohib; Tas: D Declaration status by seed. Spread mainlyby fragments, butcanreproduce Means ofspread water to 10mdeep. Widespread throughout NSW, Qld, WA andNT, in Distribution equipment inhydroelectric lakes. in New Zealand, where itblocksdamintake boating andswimming. Hornwort isproblematic nutrient-rich water fishing, andcanrestrict organisms. Itsometimesformsdensemats in provides shelter forsmallfishandotheraquatic which isafoodsource forwaterfowl and Hornwort isanative Australia water plant Background

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Photo: Suzanne Hayward 52 S Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ L Submerged to emergent perennial herb. Description Myriophyllum aquaticum P ...... species Similar looking eaves: tems: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ opposite leaves Myriophyllum Cabomba ( Ambulia ( Spreading, andhairless erect In leafaxils(stem andleafjunction) Inconspicuous emergentOn stem long, 0.5–0.8cmwide, crowded at tip Emergent: toothed, blue-green, 2.5–3.5cm Submerged: bladeupto 4cmlong Feather-like Whorled arrot’s feather Limnophila Cabomba caroliniana spp. spp.) ): submerged authority If found, thisweed report to your localweed WA: P1/2; Tas: D;ACT: C1/4 Declaration status species may become more ofaproblem. If maleplants are introduced into Australia this found inAustralia, andseedisnotproduced here. on separate plants. femaleplants Only have been fragments. Male and female flowers are produced In Australia, parrot’s feather spreads by Means ofspread coast ofAustralia from Brisbaneto Sydney. Common incoastal waterways alongtheeast Distribution flow. water andformsdensestandsthat impedewater the world. Itgrows well very innutrient-enriched Native to Americaandwidespread South around Background NO X IO U S IN SO IN S M E STATES E IN T

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FEATHERY SUBMERGED WATER PLANTS Comparison table of feathery submerged water plants H A mbulia demersum Ceratophyllum aquaticum Myriophyllum Limnophila caroliniana Cabomba Cabomba feather P arrot’s ornwort N ame spp. whorled whorled opposite whorled L eaf arrangement toothed margin toothed margin fanlike divided submerged: finely emergent: broad; L eaf description inconspicuous inconspicuous white lavender or pink, blue, white, Flower free-floating leaves submerged or emergent flowers submerged leaves, emergent leaves submerged or emergent Distinguishing featuresDistinguishing Photo: Graham Prichard Photo: Suzanne Hayward Photo: Andrew Petroschevsky Resources, Environment NT and the Arts, Photo: of Natural Courtesy of the Department I mage

54 submerged water plants ...... N on-feathery 55

Photo: Graham Prichard 56 Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ L Submerged. Description Elodea canadensis Elodea ...... species Similar looking eaves: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ alternate downwards spirals; curve straight, serrated, dullgreen of 3–8;larger leaves (upto 4cmlong),almost Lagarosiphon ( #Hydrilla ( Egeria ( maleflowersOnly in Australia 3 petals Inconspicuous whiteOn thread-like stem Bright green down slightlyBend Whorls of3(rarely 4) 0.5–1.5 cmlong, 0.2–0.5cmwide leaves (4cmlong) crowded; larger flowers (2cmwide)and Egeria densa Hydrilla verticillata Lagarosiphon major) ): leaves inwhorlsof4–5, ): leaves inwhorls : leaves in authority. If found, thisweed report to your localweed SA: 1@; WA: P1/2; Tas: D;NT: C Declaration status pieces whichare easilytransported. found inAustralia. Stems readily break into Spreads by fragments. maleflowers Only are Means ofspread northern Vic andsouth-western NSW. a majorproblem waterways inconstructed of in colder areas inNSW, Vic and Tas. Ithasbeen water bodies, coastal rivers andcreeks, especially Elodea isfoundinslow-moving andstationary Distribution growth. and hasahighlight requirement foroptimum Elodea doesnotthrive iniron-deprived water grows rapidly whentemperatures exceed 15°C. temperate zones, canwithstandfreezing and Elodea isnative America.Itthrives to in North Background # Denotes Australian native species. NO X IO U S IN SO IN S M E STATES E IN T

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Photo: Suzanne Hayward 58 Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ L Submerged, upto 1.5mlong. Description Egeria densa dense water weed Egeria/leafy elodea/ ...... species Similar looking eaves: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ (5–15 mmlong) of 3;smallerflowers (5mmlong)andleaves margin; smaller flowers (3mmlong) of 3–8;almoststraight leaves, visiblyserrated Lagarosiphon ( #Hydrilla ( Elodea ( maleflowersOnly recorded inNSW 3 petals Emergent White, 2cmdiameter clusteredDensely Minutely serrated margins 4 cmlong Whorls of4–5(rarely 3–8) alternate spirals, downwards curve Elodea canadensis Hydrilla verticillata Lagarosiphon major ): leaves inwhorls ): leaves inwhorls ): leaves in # Denotes Australian native species. authority. If found, thisweed report to your localweed NSW: 5;SA:1@; WA: P1/2; Tas: D;NT: C Declaration status been recorded inAustralia. to boating equipment. maleflowers Only have Spreads by fragments, whichare easilyattached Means ofspread streams inNSW, Qldand Vic. Found inshallow lakes, pondsandslow-flowing Distribution recreational activities. reduce aquatic biodiversity andinterfere with waterdense massesandcanrestrict flow, for aquariumsandgarden ponds. Itforms introduced into Australia asapopularplant Egeria isnative to Americaandwas South Background NO X IO U S IN SO IN S M E STATES E

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Photo: Graham Prichard 60 Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ L Submerged, to 2mlong. Description Hydrilla verticillata H ...... species Similar looking eaves: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ cm long 3, bent down slightly, bright green, 0.5–1.5 Lagarosiphon ( Egeria ( Elodea ( release pollen inanairbubbleandopens floatsto to surface Male: bud-like, reddish, inupperleafaxils; bubble andopens inanair 0.3 cm;3petals;floats to surface Female: translucent white, thread-like stem, Male andfemaleflowers ondifferent plants Summer magnification Lower finehairsvisibleunder very surface: Almost straight leaves Whorls of3–8(on samestem) Toothed margins serrated leaves; larger flower (2cmdiameter) curl downcurl inalternate spirals ydrilla Egeria densa Elodea canadensis) Lagarosiphon major ): crowded, minutely : leaves inwhorlsof ): leaves weed authority. If foundin Tas, thisweed report to your local WA: Prohib; Tas: D Declaration status bottom andgrow inspringandsummer. leaf axilsinwinter, whichbreak off, sink to the form turions(overwintering vegetative buds)in Large numbersoftubersare produced, anditcan Spreads by fragments, rhizomes andstolons. Means ofspread Australia. in warmer areas inallmainlandstates of water bodies, coastal rivers andcreeks, especially Hydrilla grows inslow-moving andstationary Distribution in theUSA. to beoneofthemostproblematic water weeds regarded asaweed inAustralia andisconsidered water Itissometimes andfishproduction. quality ofabalanced community,as part improving Hydrilla isnative to Australia andusuallygrows Background # Denotes Australian native species. NO X IO U S IN SO IN S M E STATES E

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Photo: Graham Prichard 62 S Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ L Submerged indepthsto 6.5m. Description: Lagarosiphon major L ...... # Denotes Australian native species. species Similar looking eaves: tems: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ agarosiphon serrated, almoststraight leaves #Hydrilla ( Elodea ( Egeria ( Curved at base(J-shaped) Floats Clear to white Female flower, 3petals Very small stem (except water) inhighlyalkaline Tapered downwards tipscurve towards the 0.5–2 cmlong, 0.2–0.3cmwide Alternate spirals alongthestem long; flowers 2cmdiameter Egeria densa Elodea canadensis Hydrilla verticillata ): whorledleaves to 4cm ): whorledleaves ): whorled, authority. If found, thisweed report to your localweed 1@; WA: P1/2; Tas: D;Qld:C1;NT: C;ACT: C1/4 Listplant.National Alert Vic: S;NSW: C1(S);SA: Declaration status recorded at boat ramps. boat trailers. Many infestations are often first Spreads by fragments, whichattach to boats and Means ofspread Lagarosiphon There are currently nonaturalised infestations of Distribution waterways upto depthsof6metres. underwater thickets inlakes, damsandponded New Zealand andEurope. Itcanformdense weed intemperate zones oftheworld, including be present inAustralia. However, itisamajor in thelate 1970s, andtoday itisnotknown to and eradicated inseveral locations inAustralia industry. Smallinfestations were discovered introduced into Australia fortheaquarium Lagarosiphon isnative to Africa South andwas Background inAustralia. NO X IO U S IN SO IN S M E STATES E IN T

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NON-FEATHERY SUBMERGED WATER PLANTS Comparison table of similar non-feathery submerged water plants (Hydrilla verticillata) H (Lagarosiphon major) L (Egeria densa) Egeria (Elodea canadensis) Elodea agarosiphon ydrilla N ame whorls of 3–8 alternate spirals (rarely 3–8) whorls of 4–5 (rarely 4) whorls of 3 arrangement L eaf straight almost curve down curve clustered densely bright green slightly; down curve description L eaf serrated serrated minutely serrated minutely serrated minutely margin L eaf mm wide 4 cm long, 5 mm wide long, 2–3 0.5–2 cm wide 2–5 mm 4 cm long, mm wide long, 2–5 5–15 mm L eaf size wide 3 mm 3 petals; wide 2 mm 3 petals; wide 2 cm 3 petals; wide 5 mm 3 petals; Flower margin serrated leaf leaves down curve large flowers large leaves and of 3 leaves in whorls Distinguishing Distinguishing features Photo: Graham Prichard Photo: NSW DPI Photo: Graham Prichard Photo: Graham Prichard I mage

64 ...... Floating water plants 65

Photo: Suzanne Hayward 66 with yellow spot;blackfibrous roots purple flowers withdarkpurple to blue centre floating, leaves; erect bulbousleafstalks;light Flowers: O ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ L Can befree floating. Usually rooted insubstrate to depthof 10–15 m. Description Eichhornia azurea A ...... Water hyacinth ( species Similar looking eaves: ther: ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Small seeds, 0.1–0.2cmlong Submerged stems smoothandbranched for1dayOpen andautumn Summer 6 toothed petals, 1–3cmlong water stem, 8–12cmaboveSeveral hairy onerect yellowUppermost petalhasdistinct spot White to lavender-blue S cm long, 2–16cmwide Emergent: broad generally very ovate, 5–16 Leaf stalks(petioles)are smooth;notinflated nchored water hyacinth 6–20 cmlong, 1cmwide ubmerged shade:strap-like, orinheavy Eichhornia crassipes ): free- creeks, lakes andotherwater bodies. can grow of quicklyandsmotherthesurface authority. If found, thisweed report to your localweed NSW: C1(S); WA: Prohib; Qld:C1 Declaration status a newinfestation. breaks away andmoves downstream andstarts birds. Coverage oftheplant spreads whenpart be carriedby water, inmud, onvehicles andby Reproduces by fragments andseed. can Seeds Means ofspread territories. a majorpestinwaterways inallstates and water hyacinth hasthepotential to become If introduced andallowed to spread, anchored Distribution ( world’s worst aquatic weeds, water hyacinth America.ItiscloselyrelatedSouth to oneofthe Anchored water hyacinth isnative to tropical Background Eichhornia crassipes NO ). Anchored water hyacinth X IO U S IN SO IN S M E STATES E IN T

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Photo: NSW DPI Photo: NSW DPI 68 S ■ ■ ■ ■ ■ ■ ■ ■ ■ L Free-floating fern,1–2.5cmdiameter. Description spp.Azolla A ...... species Similar looking eaves: tem ■ ■ ■ ■ ■ ■ ■ ■ ■ #Duckweed ( ( Salvinia pinnata A. filiculoides A. triangular shape Branches longertowards base, givingplant Main stem withpinnate branches shade Older leaves canbered insunlight, green in Lobes 0.2cmlong Tiny, scale-like, 2-lobed stage zolla Salvinia molesta : fine rootlets present : fine rootlets absent Lemna spp. and ): primary growth ): primary Spirodela spp.) Do not report thisplant. notreport Do Not declared aweed inAustralia. Declaration status fragments. Azolla produces spores andcanspread by Means ofspread each state andterritory. waterways, and at leastonespeciesisfoundin Azolla isfoundinslow moving andstationary Distribution levels are adequate. water ifnutrientsstationary bodies, particularly to cover openareas ofwater andmay buildupin fields inAsiaasafertiliser. Itcanquicklyspread plants decay. Azolla isoften grown inpaddy the fronds. This nitrogen isreleased whenthe cyanobacterium in anitrogen-fixing supports used asadecorative feature ingarden ponds. It common inmany waterways andiscommonly Azolla isanAustralian native fernthat is Background # Denotes Australian native species.

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FLOATING WATER PLANTS ©University of Florida Center for Aquatic and Invasive Plants ©University of Florida Center for Aquatic and Invasive Plants

70 Photo: Jessica Grantley Photo: Jessica Grantley ■ ■ ■ ■ ■ Flowers: as green mat onsurface. Tiny, free-floating plants.Dense growth appears Description Lemna spp., Wolffia spp., Spirodela spp. Duckweed ...... species Similar looking ■ ■ ■ ■ ■ #Azolla ( ( Salvinia Spirodela Wolffia Tiny, white, barely visible stage and branches spp:<0.1cm A. filiculoides A. spp:to 1cm Salvinia molesta and ): primary growth ): primary A. pinnata A. ): stem # Denotes Australian native species. thisplant. notreport Do Not declared aweed inAustralia. Declaration status Duckweeds spread mainlyby fragments. Means ofspread few speciesfoundineachstate andterritory. Slow-moving waterways, andstationary witha Distribution aquatic animals. They foodsource are animportant forbirds and on thewater innutrient-rich conditions. surface plants onEarth. They canformadensegreen mat countries andincludethesmallestflowering Duckweeds are native to Australia andother Background

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FLOATING WATER PLANTS Photo: NSW DPI

Photo: Suzanne Photo: Andrew Petroeschevsky 72 Hayward midrib leaves 3 growth stages: buoyancy) ■ ■ ■ ■ ■ ■ ■ ■ ■ L Free-floating fern. Description molesta Salvinia Salvinia ...... less thanaweek. temperatures andnutrients candoubleitssize in garden ponds. Itcangrow rapidly, andwith high during the1950sasanornamental plant for believed to have beenintroduced into Australia isnativeSalvinia to Americaanditis South Background confused with: growthThe stageofsalviniamay primary be species Similar looking eaves: ■ ■ ■ ■ ■ ■ ■ ■ ■ #Duckweed ( #Azolla ( Tertiary: crowded plants; leaves foldedat to leaves foldat midrib Secondary: start isolatedPrimary: plants; small, flat, oval Eggbeater-shaped hairsonupper ‘leaf’ surface (repels water surface andaids Hairy Light green; oval Opposite Azolla Lemna spp.) alternate leaves spp., Spirodela spp.) # Denotes Australian native species. authority. If found, thisweed report to your localweed P1/2; Tas: D;Qld:C2;NT: B/C;ACT: C1/4 WoNS. Vic: S;NSW: C2(106)/C3(22);SA:1@; WA: Declaration status farm damsorby aquatic plant enthusiasts. through deliberate useasanornamental plant in onboatingactivities, andfishingequipment, and spreadsSalvinia mostlythrough human rhizomes break through decay ordamage. Spreads by fragments. New plants formwhen Means ofspread waterways inallstates andterritories. potential to spread to stillandslow-moving infestations are foundinNTand WA. Ithasthe east coast from Cape York toNSW. Bega, Other isfoundalongmuchofAustralia’sSalvinia Distribution WEED OF NATIONAL SIGNIFICANCE NATIONAL OF WEED 73

74 water caltrop: Roots: Fruit: S Flowers: ■ ■ ■ ■ ■ ■ ■ ■ ■ L substrate. Floating rosette withastem attached to Description Two speciesofthegenus Trapa spp. W ...... eaves: tems: ■ ■ ■ ■ ■ ■ ■ ■ ■ bicorinis Feather-like to 8cm Contains asingleseed Woody, 3cmwide, 4spines(1cmlong)( Unbranched to 3.6–4.5mlong Early summer White; 4petals, 0.8cmlong Emergent shape hairsonlowerformrosette surface; short toothed margins, fine glossyuppersurface, Floating: triangularshape, 2–3cmlong, Submerged: finelydivided, feather-like ater caltrop has2spines) T. natans and Trapa T. bicornis. are referred to as T. authority. If found, thisweed report to your localweed 1@ T. natans) NSW: C1(S); WA: Prohib; Tas: D; Qld: C1; NT: C; (SA: Declaration status other animals. floating away by birds orbeingtransported or breaking away, andby fruitsdetachingand 12 years. Water caltrop canspread by therosettes 15–20 seeds. The seedsremain viableforupto 10–15 plant rosettes, andeachrosette produces Reproduces by seed. Each seedcanresult in Means ofspread Not yet recorded withinAustralia. Distribution the fruitare hazardous to humansandanimals. across wideareas ofwater. The sharpspinesof and eaten inChina.Itformsimpenetrable mats ofEurasia andAfrica.parts The seedsare cooked Water caltrop isanative ofwarm-temperate Background NO X IO U S IN SO IN S M E STATES E 75

Photo: Qld DPI & F 76 O Flowers: ■ ■ ■ ■ ■ ■ ■ ■ L Erect, free-floating, 10cm to 1mtall. Description Eichhornia crassipes W ...... and isamajorweed ofwaterways throughout Water hyacinth isanative America ofSouth Background species Similar looking eaves: ther: ■ ■ ■ ■ ■ ■ ■ ■ Anchored water hyacinth ( Black fibrous root system Leaf stems (petioles)bulbousandspongy Cluster onspike above theplant with yellow spot Light purplewithdarkto bluecentre Ovate to circular, to 5cmdiameter andglossy Thick, waxy Dark green submerged leaves flower, nobulbousleafstem, strap-like generally rooted inmud, yellow spoton ater hyacinth Eichhornia azurea ): infrastructures, includingfences andbridges. weight moving alongawaterway canthreaten in large quantities offloating biomass. This providing shelter formosquitoes andresulting in size inafewweeks, altering aquatic habitats, plant. Inwaterways aninfestation candouble was asanornamental mostlikely imported Brisbane, Sydney andGrafton inthe1890sand the world. Itwas firstnoticed in Australia in authority. If found, thisweed report to your localweed P1/2; Tas: D;Qld:C2;NT: A/C;ACT: C4 Vic: S;NSW: C2(101)/C3(17)/C4(9);SA:1@; WA: Declaration status increased itsspread around thecountry. asanattractivepopularity garden pondplant has days orremain dormant forupto 15years. Its quantities ofseed. cangerminate Seeds inafew Spreads by fragments andproduces vast Means ofspread in allmainlandstates ofAustralia. Found inslow-moving waterways andstationary Distribution NO X IO U S IN ALL STATES ALL IN S 77

Photo: Brian Worboys 78 Flowers: ■ ■ ■ ■ ■ L Free-floating, to 15cmtalland30wide. Description Pistia stratiotes W ...... cool waters. Itisfrostsurface. sensitive anddoesnotthrive in nutrient levels to formlarge mats onthewater rapidly undertropical conditions andadequate but isintroduced inQldandNSW. Itcangrow Water lettuce isthought to benative to theNT, Background Floating mats ofwater lettuce canresemble: species Similar looking eaves: ■ ■ ■ ■ ■ Water hyacinth ( ( Salvinia leaves Inconspicuous, onsmallstalkhiddenamongst Thick; covered hairs withshort Overlap like alettuce ater lettuce Salvinia molesta Eichhornia crassipes ) ) authority. If found, thisweed report to your localweed NSW: C1(S); WA: P1/2;Qld:C2;NT: B/C;ACT: C1/4 Declaration status plant andissometimesfoundforsale. at theend. Ithasbeenapopularornamental produce stolons, whicheachproduce anewplant Reproduces by fragments andseed. Plants Means ofspread the NT, NSW. Qldandnorthern Found inslow-moving waterways throughout Distribution NO X IO U S IN SO IN S M E STATES E 79

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