Resource sheet 2 - Willow identification - Weeds Australia

Weeds of National SignificanceWillow IdentificationAn essential skill for successful willow managementWillow Resource Sheet : 2RSupported by the State Government of Victoria

Weeds of National SignificanceWhy identify willows?Implications for managementWillow invasion dynamicsDifferent willows vary in their ability to spread intoand thrive in new environments. It is importantto understand how different willows spread andto adapt management programs accordingly.Willows can either spread sexually (via seed) orvegetatively (via twigs and branches) or by bothof these means. The seeds germinate on bare, wetsediments, while branches, attached or detached,root mainly on wet ground or in shallow water.♦ Spread by seedThe ability of willows to spread by seed dependsmainly on the availability of favourable seedbeds(bare, wet ground) and the overlap in floweringtimes of compatible female and male plants.A female willow can produce thousands ofseeds each spring. However, often these seedsdo not germinate or grow, possibly due to thelack of suitable seedbed, rising or rapidly fallingwater levels and floods that uproot or bury theseedlings.Suitable conditions for seedling establishmentlikely occur in most temperate Australian streamsevery 5 to 20 years . Major disturbances, suchas wildfire or the collapse of a swamp can alsopromote massive seed germination. Thus, whilespreading by seed may appear restricted for manyyears, a catastrophic explosion of seedlings mayoccur at any time, given the right conditions.Some willows can spread by seed up to 50-100km.These willows may spread rapidly across regionsand states, so even the most remote environmentsare at risk of invasion.The ability of willows to spread largedistances by seed highlights the need forcoordinated action across regions andstates to prevent further spread.♦ Control of seeding willowsEarly identification and control of seeding willowsis critical and should be made a high priority formanagement. In some cases, such willows willneed to be immediately controlled in areas wherethey do not currently cause significant impacts,to prevent them from spreading to other, moreimportant environments.Hybridisation between willows generally onlyoccurs between plants within the same subgenus .Almost all willows are able to hybridise with atleast one or more other willows, so long as theyflower at the same time and fertile male andfemale plants grow near enough for pollination tooccur.We are not sure exactly how far willow pollencan travel (by insects or wind) and successfullypollinate a female plant. Although bees may flyup to 3 or 5 km to collect pollen and nectar, itis thought that cross-pollination is generallyrestricted to much smaller distances (e.g. 50 m).However, female plants growing 1km from thenearest male have been observed producingviable seeds . It is therefore recommended thatmale plants be separated from females by at least2 km and preferably more if possible.If you find female and male willows from thesame subgenus (‘tree’ or ‘shrub’) within a fewkilometres of each other, remove all female plantsimmediately.To stop willows spreading by seed, it is essentialto at least identify the gender (male, femaleor both) and subgenus (shrub or tree) of eachwillow and whether it is producing viable seed.Kurt Cremer, personal observationOne exception is S. x mollissima – a cross between S.viminalis (subgenus Vetrix) and S. triandra (subgenus Salix).S. triandra is not yet naturalised in Australia however.Kurt Cremer, personal observation2

Willow identification♦ Spread by branches/twigsSome willows can readily reproduce by twigsbreaking off at the base of the stem and takingroot downstream. In addition, dense layeringof willows can occur where trunks collapse orbranches hang down and form new roots wherethey touch the soil.The brittleness (or ‘fragility’) of a branch/twig isthe most important feature determining a willow’sability to spread aggressively by vegetativemeans. Brittleness is determined by the ease withwhich the branch can break at its base – the restof the branch may be quite flexible. Many of thetree willows in Australia are easily broken at thebase. The shrub willows are generally less fragileand are therefore less likely to spread by thismethod.Crack willows (Salix fragilis) have extremely‘fragile’ branches that snap easily at the base, withan audible ‘crack’. S. fragilis and related hybridshave spread aggressively and are currently themost widespread and abundant willows, occupyingthousands of kilometres of streams across southeasternAustralia.The brittleness (or ‘fragility’) of a branch/twigis the most important feature determininga willow’s ability to spread aggressively byvegetative means.♦ Controlling spread by branchesAs with seeding willows, careful planning,management, revegetation and follow up weedcontrol are crucial to ensure that these willows aremanaged effectively. It is important to rememberthat:• if willows or other weeds are removed from anarea, twigs and branches from upstram mayeasily spread downstream and reinvade thearea where the willows (or other weeds) werejust removed;• when controlling these willows, it is criticalto ensure that all branches and other livematerial are removed - otherwise a multitudeof new willows may sprout from the remainingmaterial;• removing these willows may expose an idealseedbed for seeding willows to colonise, unlessrevegetation occurs quickly.To stop the spread of willows by branchesand twigs, it is important to identifywillows with brittle branches that aregrowing along waterways.Impacts of willowsWillows infest thousands of kilometres ofwaterways across southeast Australia and causesubstantial social, economic and environmentalimpacts such as:♦ reducing the quality and flow of water,♦ increasing erosion and flooding and causingdamage to nearby infrastructure,♦ reducing available habitat for fish, birds, insectsand spiders and♦ obstructing access to streams for fishing andaquatic sports.Willows clearly need to be managed to reduce thecurrent impacts they are causing, as well as toprevent future spread. Many regional CatchmentManagement Authorities (CMA) or NaturalResource Management (NRM) bodies address theimpacts of willows on river health through theimplementation of their Regional River HealthStrategies.Current/potential distributionWillows impact upon thousands of kilometres ofwaterways, wetlands, drainage lines and othermoist areas across Victoria, New South Wales,the ACT and Tasmania. They are also known tooccur to a much lesser extent in South Australia,southern Queensland and Western Australia.Information on the current distribution of willows,including the gender, subgenus and, in somecases, species is essential for planning an effectivewillow management strategy. Such information isseriously lacking in all states/territories.The extent of willow infestation in Australiahas not been well documented and recordsthat do exist often lack key informationnecessary for effective management.Willow management prioritiesEradication of willows across Australia is notfeasible or desirable. Instead, we need to prioritisethe selective removal of undesirable willows. Ingeneral, willows should be prioritised for controlif they are:♦ female willows growing near male plants(within about 2km) and/or producing viableseed;♦ ‘fragile’ willows (that is, with branches thateasily break off) growing along waterways;♦ causing impacts to river health or other social,environmental or economic values.To do this, we require information on the gender,subgenus and brittleness of all willows.3

Weeds of National Significance1. Is the plant male, female or both?Most willow plants are either male or female,with a few rare exceptions where both male andfemale flowers occur on the one plant. If plantsof both sexes are present in a locality, pollinationcan result. It is therefore important to know thesex of willows, as an indication of their ability tospread by seed.The sex of the plant can be determined inspring when flowering occursWillows flower for approximately 3 weekseach year between the months of August andNovember. Flowering times vary among speciesand according to climate. In general, if a male andfemale plant from the same subgenus (i.e. ‘tree’,‘shrub’ or ‘alpine’) flower at the same time, theycan hybridise and form new plants.Willow catkinsCatkins are influorescences comprising of 100or more male or female flowers. Female flowersproduce nectar only, whereas male flowersproduce nectar and pollen. It is believed thatinsects mostly pollinate the flowers (attractedby the nectar), but it is possible that some windpollination may occur.A simple way of determining if the catkinis male or female is to remember thatonly males produce pollen.Male flowers have stamens that consist of a finefilament tipped by two yellow pollen sacks,which release yellow pollen when mature. Femaleflowers, on the other hand, each have a singlebulbous green ovary topped by a stigma. Thisovary later matures into a capsule that splits openand releases fluffy seed.Willow seedlings growing along the King River,North East Victoria. The seed of some willows canspread long distances by wind, so even the mostremote environments are at risk of invasion.Male: Each flower on a male catkin has several stamens, which consist offine filaments with bright yellow pollen sacs at the tipsMale catkinMale flowerFilamentPollen sackAbove: Male catkin from a crack willow (Salix fragilis var. fragilis). Each flower has 2 or more stamens, each consisting ofa fine filament and bright yellow pollen sack (Photo: Matthew Baker)4

Willow identificationWeeds of National SignificanceFemale: Each flower on a female catkin has a singlebulbous green ovary topped by a single stigma.Female flowerFemale catkinStigmaOvaryAbove: Female catkin from a grey sallow (Salix cinerea). Each flower has a bulbous green ovary and is topped by a singlestigma (Photo: Matthew Baker).Catkins can vary in size and shape between willow species.For example, Salix cinerea has egg-shaped catkins, whileSalix alba has long, slender catkins.Above: If pollinated, female catkins producelots of fluffy seeds that can be dispersedlong distances by wind.Above: (left) Male Salix cinerea catkins and (right) female Salixalba catkins. Note: (right) the ‘tree’ willow’s leaves have emergedwith the catkins and (left) there are no leaves on the stem asthe ‘shrub’ willow’s catkins have emerged before the leaves.Male and female flowers on the same catkin!In some rare instances, male and female flowers can form on the same plant and sometimes even on the samecatkin. The golden weeping willow (Salix x sepulcralis var. chrysocoma) and the New Zealand hybrids (Salixmatsudana x S. alba) can both develop male and female flowers on the one plant. This allows the plant tofertilise its own flowers, enabling a single, isolated tree to set viable seed.Male flowerFemale flowerAbove: Catkins with both male and female flowers from (left) a golden weeping willow (Salix x sepulcralis var.chrysocoma) and (right) a New Zealand hybrid willow (S. matsudana x S. alba).5

Weeds of National SignificanceWhen do willows flower?Flowering occurs between August and November, but the precise timing varies among willow taxa. Somewillows commence flowering in August, while others do not flower until late September and October. Thefollowing table illustrates the approximate flowering times of different willows, based on data collected in theACT from 1995-19991. Actual flowering times may vary considerably, however, depending on variations intemperatures between years and across regions and states.Tree willowsAugust September October NovemberS. babylonica ♀ OoooooooiooooooooooooooooooooooooooooooooooooooS. × chrysocoma ♂ OooooooooooooooooooooooooooooooS. matsudana × alba ♂ Ooooooooooooooooooooooooooooooooooooooooooooooo♀S. alba ♂ ♀OooooooooooooooooooooooooooooooooooooooooooooooooS. fragilis ♂OooooooooooooooooooooooooooooooooooooooooS. matsudana ‘Tortuosa’ Oooooooooooooooooooooooooooooooooooooooooooooooooooooooo♀S. × rubens ♂ ♀ OooooooooooooooooooooooooooooooooooooooooooooooooooooooooooS. alba var. vitellina ♀ OoooooooooooooooooooooooooooooooooooooooooooooooooooooooooooS. nigra ♂ ♀ OoooooooooooooooooooooooooooooooooooooooooooooooooooooooooooooShrub willowsS. × reichardtii ♂S. viminalis ♂ ♀S. purpurea ♂ ♀S. cinerea ♂ ♀Oooooooooooooo O ooooooooooooooooooooooooOoooooooooooooooooooooooooooooooooooooooooooooooooooooOoooooooooooooooooooOOooooooooooooooooooooooooooooOoooooooooooooiooooooooooooooooooooooooooooooooooooooooooo1Data obtained by Cremer (1995 and 1999) in the ACT between 1994 and 1998.♀ - forms female catkins ♂ - forms male catkinsooooo = Catkins enlarging ooooo = Flowering ooooo = Seed development ooooo = Seed shed2. Is the seed viable?If both female and male plants from the same subgenus (e.g. Salix or Vetrix) are present in an area and theirflowering times overlap, pollination is likely to occur and viable seed produced.To confirm if viable seed is being produced:1. Collect branches with catkins that have started to release white, cottony fluffbut also have unopened capsules.2. Place cut ends in a vase of water as you would do with a bunch of flowers.3. Keep in a sheltered room and wait until the new capsules open and release fresh seed(usually only a day or two).4. Select 10–20 seeds, with or without attached cottony fluff.5. Press firmly into very wet tissue paper on a dish so that seed makes close contact with the wet paper.6. Cover dish with glass or plastic wrap so that the seed keeps moist, but not dark.7. Keep at room temperature (20–25 o C) in a well-lit position, but not in direct sunlight.8. Germination is usually obvious after 1 or 2 days – a pair of 1mm long green leaves will appear.Some willows can spread by seed up to 100km, emphasising the need forearly identification and management of seeding willows.6

Weeds of National Significance73. Is the willow a ‘tree’ or ‘shrub’?If both female and male plants from the same subgenus (either ‘shrub’ or ‘tree’) are present in an area and their flowering times overlap, pollination is likelyto occur and viable seed produced. Identifying which of these major groupings (or subgenera) the willow belongs to will help prioritise where resourcesshould be allocated for management. The following table outlines some features that can generally be used to distinguish between tree and shrub willows.It is important to note, however, that there are some exceptions to the rules.Shrub willows - osiers vs pussy willowsBoth osiers (e.g. common and purple osiers) and pussy willows (e.g. grey sallow and pussy willow) belong to the subgenus Vetrix (shrub willows). Osiers aresimilar to pussy willows in having many stems, flexible branches, generally rather smooth bark and dark flower scales (you will only be able to see flowerscales with an eye glass or microscope). However, osiers have several features that resemble tree willows (subgenus Salix). Like tree willows, osiers generallyhave long, narrow leaves and catkins and, in some cases, the catkins of the common osier (Salix viminalis) emerge with the leaves, a feature otherwise onlyseen in ‘tree willows’.Shrub willows (osiers and pussy willows)(subgenus Vetrix)Tree willows(subgenus Salix)The pussy willows include Salix cinerea, Salix x reichardtii. Theosiers include Salix purpurea and Salix viminalisIncludes Salix fragilis, Salix nigra, Salix babylonica and Salix alba var.vitellinaMulti-stemmed low shrub to small tree4–9 metres tall at full sizeForm Single to multi-stemmed tree or shrub10–20 metres tall at full size; weeping or upright♦ Do not break easily – branches flexible at the base♦ Generally break easily at the base – some may crack more easilythan others♦ Generally rough or fissuredStems♦ Generally rather smooth, but can become somewhat fissuredwith ageBark

Leaves ♦ Long and narrow, shaped like a canoe when seen from above♦ Toothed margins♦ Length usually more than 3x the width♦ Silky or hairlessOsiers:♦ Thin, long and narrow, usually 5-10times longer than wide♦ Margins usually smooth, sometimes irregularlytoothedPussy willow OsierCatkins ♦ Emerge with the leaves, hence leaves and catkins both present on thestems♦ Slender and cylindrical, upright or sometimes drooping♦ Flower scales pale green or yellowPussy willows:♦ Thick, generally oval to elliptic inshape♦ Irregularly toothed margins, hairy withconspicuous veins beneath♦ Usually less than 3 times longer thanwidePussy willowYellow flower scaleOsiers:♦ Long, cylindrical, 1.5-5cm long, closely spaced along one-yearoldshoots, may emerge before or with the leavesPussy willows:♦ Short and oval-shaped and produce lots of fluffy seed♦ Emerge well before the leaves, hence no leaves are seen onthe stems; flower scales darkPussy willow OsierFemale Male8

Weeds of National Significance6. How to collect a willow specimen?If you are uncertain about the willow species (orvariety or hybrid) you are dealing with, collecta specimen and send it to your local herbariumor expert for advice (see Further Information forcontact details). Sending a plant sample to theherbarium has the added benefit of establishinga permanent record of that plant at a particularlocation and time. This assists our understandingof the distribution and ecological preferences ofthat species.Remember, it takes almost as much effort toprepare a poor specimen as it does to prepare anexcellent specimen.For accurate identification of willows, completespecimens should be collected at two periods ofthe year - in the spring for catkins (or flowers) andin the summer or early autumn for mature foliage.If a site can only be visited once, collect materialin the summer or early autumn, as leaves providemore valuable information for identification thancatkins do.If you discover willow seedlings in an area,collect specimens of likely parents growing inthe neighbourhood also, to aid identification andmanagement.1. Complete a label that includes the informationoutlined on the right;2. Collect a healthy specimen (approx. 30cmlong), with leaves and twigs. If possible,return in spring to collect catkins and/or seedbearing capsules;3. Take a photo of the tree form and bark;4. If specimen is dirty, gently clean it with waterand dry;(Note: if you do not have paper with you whencollecting, place specimen in a dry plastic bag andpress within 24 hours)5. Place specimen between several sheets ofnewspaper;6. Arrange the specimen so that all parts can beclearly seen (stems and both sides of leaves);7. Place weights on specimen to apply pressureand flatten the specimen;(Note: this can be done with objects such as booksor boards with bricks on top);8. Change newspaper daily for the first few days,then weekly until dry;9. When dry, put specimen between 2 sheets ofnewspaper, then 2 sheets of firm cardboard;10. Place catkins and/or seed in a labelledenvelope with specimen;11. Check that the specimen is correctly labelled;12. Securely wrap package;13. Attach a letter with your contact details andrequest for identification.LabelThe information recorded on the label is asimportant as the specimen you collect.For each specimen collected, attach a label withthe following information.Example only: Four Specimen Information lables areavaliable on the back of this bookletfor photocopying.Specimen informationNumber (year/month/day/sequential number):______________Name:_________________________________________________Date:_ _________________________________________________Precise location (on a map or latitude/longitude or easting/northing):______________________________________________________________________________________________________Town:________________________________ State:___________Growth form (e.g. tree, shrub; weeper, non-weeper):_______________________________________________________Number of trunks (emerging from base):__________________Height (m):____________________________________________Bark texture (rough or smooth) & colour:_________________________________________________________________________Colour:fresh stems ____________________________________leaves – upper ____________________________________leaves – under ____________________________________catkins (flowers) ____________________________________roots (if visible) ____________________________________Habitat (e.g. riverbank, wetland, grazed paddock, drainageline, riparian forest etc.):_________________________________________________________________________________________Abundance of mature plants (no./ freq. of plants) andpresence of seedlings:_________________________________________________________________________________________Other info (e.g. damage to tree, growing in stream or alongbank etc.):_____________________________________________________________________________________________________________________________________________________________________________________________________________10

Salix fragilisCrack willowSalix nigraBlack willowDistinctive glossy, greenish brown,hairless twigs snap off at base veryeasily with a loud crack. Bright red/pink rootlets in water.S. x rubens can look very similar.Salix x rubensGold-crack willowDeeply fissured grey bark on stemsover 10cm diameter and leavesalmost equal bright green on bothsides. Spreads aggressively by seedand branches in NSW and Vic.Distinguishingfeatures♦ Up to 20m high♦ Broad rounded crown, widespreading branches♦ Trunk divides into major branchesat ground levelSalix alba var. vitellinaGolden willowA hybrid of S. fragilis and S. alba,with appearance intermediatebetween. One of the most abundantand widespread willows. Both sexesoften present, rootlets pink or partlypink in water.♦ Up to 20m tall♦ Crown conical when young, broadwhen old in isolation♦ Usually with a single prominentstemHabit/form• Height• Shape of crown• Number of stems♦ Rough and fissured with age♦ Greyish-brownWeeds of National SignificanceYellow or orange-yellow twigs, widespreading crown, slightly hairyon underside of mature leaf anddistinctive white rootlets in water.Older twigs not brittle at point ofattachment.♦ Up to 20-25m high♦ Broad rounded crown, spreadingbranches♦ 10-20+ apparently independentstems, which are actually lowbranches emerging from theaccumulating sediment♦ Up to 15-20m high♦ Open crown and spreadingbranches; may weep in lowercrown♦ Usually with a single stem♦ Rough and fissured with age♦ Greyish-brown♦ Rough and fissured with age♦ Greyish-brown11Tree Willows - Upright♦ Usually deeply fissured on stems>10cm in diameterBark• Roughness• Colour

Salix x sepulcralis var. chrysocomaGolden weeping willowSalix matsudana ‘Tortuosa’Tortured willowSalix babylonicaWeeping willowSalix matsudana x albaNew Zealand hybridStrongly twisted outer branches,twigs and leaves. Bright green foliageand very short cylindrical catkins. Acultivar of S. matsudana.Single-stemmed, erect, steeplybranched, narrow crown, culminatingin a tip. Twigs flexible and not readilydetaching. Not yet common. Spreadseasily by seedGolden or greyish yellow twigs andsometimes both sexes on samecatkins. Catkins on stalks 1-5mmlong. Long weeping branches andriver narrowing habit.Dense foliage and long, slender,weeping twigs that often touch theground in mature plants. Earliestflowering tree willow. Can formhybrids with S. alba and S. fragilis.Distinguishingfeatures♦ Tree to 15-20m high♦ Narrow rounded crown, erect butouter most branches sometimesslightly weeping.♦ Tall tree to 25m high♦ Narrow or moderately spreadingapical-shaped crown; erectbranches♦ Single prominent stem to topof treeWeeds of National Significance♦ Tree to 15-20m high; equalheight to width♦ Wide-spreading rounded crown;long weeping branches♦ Tree to 15-20m high; taller thanit is wide♦ Wide-spreading, rounded crown,very weeping branches♦ Fissured with age♦ Grey-brown to dark brown♦ Moderately fissured with age♦ Grey13Tree Willows - Upright and WeepingHabit / form• Height• Shape of crown• Number of stems♦ Moderately fissured with age♦ Grey-brown to dark brown♦ Fissured♦ Grey-brown to dark brownBark• Roughness• Colour

♦ Reddish green, becominggrey-green or reddish-brown♦ Slender; spreading or erect;slightly to moderately brittle♦ Becoming hairless♦ Lustrous green to dark reddish,finally brown♦ Moderately brittle, slender,spreading or erect♦ Hairy at first, becoming hairless♦ 9-14cm long, 1-1.7cm wide;lanceolate; serrated edges♦ Light green to bluish green; silkyhairy when young, becomingsparsely hairy above♦ 8-13cm long, 1-2.5cm wide, narrowand long, tapering to a thread;margins finely serrated, bladesmarkedly twisted and buckled♦ Bright green above, often bluegreenbelow; silky hairy at first,soon becoming hairless♦ Golden yellow to greenish yellowfor more than 1m from tips♦ Slender, moderately brittle♦ Silky when young then hairless♦ 7-18.5cm long, 0.8-2.9cm wide;narrow-long to narrow-elliptical;pointed but not drawn out;fine serrations on edges♦ Bright green above; bluish-greybelow; silky on both sides at first,becoming hairlessShoots/twigs• Colour• Brittleness/flexibility• Hairiness♦ Male, female or both sexes on thesame catkin♦ Narrow, cylindrical, 2-3.5cm longand 6-12mm wide♦ Appears with or after leaves inSeptember-October, similar to S.babylonica and S. alba♦ Female only♦ Short, cylindrical, 2cm long♦ Very dark bud scales♦ Flowers late Sept-Oct with or afterleaves. Hybridises with S. fragilisand S. matsudana x alba♦ Seed produced has low viability♦ Male, female or both sexes onsame catkin♦ 2-5cm long, narrow, cylindrical andslightly curved; distinctly stalked(1-5mm); ovary not much longerthan pale yellow catkin scale♦ Flowers September-October♦ Greenish or brownish green♦ Long, slender, weeping♦ Hairs when young, becominghairlessLeaves• Size and shape• Colour on bothsides and degree ofhairiness• Time it emerges♦ 7-18cm long, 0.5-2.5cm wide;fine serrations (or bumps) onmargins; leaf tips drawn outand wavy♦ Slightly shiny, medium greenabove; bluish grey below; hairsat first, becoming hairless♦ Female only♦ Narrow, cylindrical and oftencurved; 0.6-2.8cm long, almoststalkless♦ Usually appears with butsometimes after leaves; flowersearly in August-SeptemberCatkins/flowers• Male/Female/both• Size and shape ofcatkins• Time it emerges14

Salix viminalisCommon osierSalix x reichardtiiPussy willowSalix purpureaPurple osierSalix cinereaGrey sallowHybrid between S. caprea and S.cinerea. Variable in its characteristicsbut generally differs from S. cinereain having longer leaves with morepointed tips, very showy, silvercatkins and being taller than it is widewhen mature.Longitudinal ridges on the woodbeneath the bark (sometimes visibleon the outside of smooth branchesalso). Wide rounded crown (widerthan it is high). Oval shaped leaves.Branches flexible. Can spread by seed10’s of kilometres from the initialsource.Long, narrow leaves, dark greenabove, pale silky below, withtoothless inrolled margins. No ridgesbeneath bark. Stigma cut in two forabout half its length. Leaves not bitterto taste.Many leaves opposite or semiopposite,especially near shoot tips;leaves wider above the middle (kiteshaped) and bitter to taste. Clumped,multi-stemmed habit, young twigssometimes purplish.Mainly occurs in the Snowy Mountainsregion.Distinguishingfeatures♦ 6-12m high, significantly higherthan it is wide♦ Several upright stems arising froma short trunk♦ 6-12m high♦ Wide, rounded crown (much widerthan high in mature trees)♦ Several sturdy branches arisingnear ground levelWeeds of National Significance♦ To about 8m high, but usually 3-6mhigh♦ Erect form♦ Several upright stems♦ To about 8m high♦ Variable in habit, from erect tospreading, often with slender,graceful branches♦ Rather smooth♦ Greyish-brown♦ Rather smooth♦ Grey, inner bark yellow15Shrub Willows - Pussy Willows and OsiersHabit / form• Height• Shape of crown• Number of stems♦ Rather smooth, shallowly fissurednear base♦ Greyish-brown♦ Rather smooth at first, becomingfissured with ageBark• Roughness• Colour

♦ Greenish, greyish, redish or purple♦ Not brittle, long striations/ridgesvisible on wood beneath bark (mayneed to peel the bark to see theridges)♦ Usually hairy at first, becominghairless♦ Olive to reddish-brown♦ Not brittle; smooth with a fewshort striations/ridges beneathbark♦ Very hairy when youngShoots/twigs• Colour• Brittleness/flexibility• Hairiness♦ 2-7cm long, 1.5-3.5cm wide,generally oval, broadest in middle,sometimes elliptic; tip short,pointed; margins sparsely andirregularly toothed.♦ Hairy both sides; dense grey hairsbelow or sometimes sparselycovered in reddish brown hairs♦ Emerge late September aftercatkins♦ Male or female or both♦ Male flowers ovate in shape andwhite with yellow tips; femaleflowers green and cylindric-ovate inshape♦ Begin to emerge in late Augustbefore the leave (earlier than mostother willows) and shed lots ofseed 4 weeks after floweringFemaleMale♦ 4-10cm long, 2.5-5.5cm wide; ovalto elliptic; margins rippled andsparsely toothed, leathery, broadestabove middle♦ Mid-green above, becominghairless except for midribs♦ Male only, but may hybridise withfemale S. cinerea♦ Broad, oblong catkins, 2-3.5cmlong with red buds♦ Emerge before leaves♦ Green to yellowish green;sometimes yellowish brown toreddish brown, especially whenexposed to the sun♦ Slender and very tough andflexible; no striations beneath bark♦ Densely hairy at first, becominghairless♦ Rather erect, long and narrow,6-18cm long, 0.5-2cm wide;margins not toothed and oftenrecurved♦ Dark shining green above; usuallycovered with whitish or greyishsilky down below♦ Juvenile leaves often longer andnarrower than older leaves♦ Male or female♦ Cylindric, 1.5-6cm long and 0.5-1cm wide, stigma cut in two forabout half its length (bifid)♦ Appear before or as leaves emergein August to October, depending onaltitude♦ Grey-green to yellowish green;sometimes yellowish brown,reddish brown or purple whenyoung♦ Long, straight, very tough andflexible♦ Densely hairy at first, becominghairlessLeaves• Size and shape• Colour on bothsides and degree ofhairiness• Time it emerges♦ Long and narrow, 2.5-11cm long,0.5-2cm wide; often oppositetowards the tips of the shoot;mostly broadening above themiddle and minutely toothedtowards the tip♦ Dark glossy green above;bluish green or glaucous below;sometimes hairy when young,becoming hairless♦ Male or female♦ Narrowly cylindric, often curved;male catkins 1.5-3cm long; femalecatkins 2-4cm long; often insemi-opposite pairs♦ Emerge before leaves in August toSeptemberCatkins/flowers• Male/Female/both• Size and shape ofcatkins• Time it emerges16

Willow identificationFurther informationRelevant weblinks:For further information on willows and links toother willow-related websites go to:www.weeds.org.au/WoNS/willowsFurther reading/references:Cremer, K.W. (1995). Willow identification forRiver Management in Australia. Technical PaperNo. 3., CSIRO Division of Forestry, Canberra,Australia.Australia’s Virtual Herbarium provides links toState and Territory herbarium websites:www.anbg.gov.au/avhAcknowledgements:Thank you to the following people for generously supplying pictures;Matthew Baker, Kyla Finlay, Fiona Ede, Terry McCormack, Jamie Davies, Robin Adair, Sarah Holland Clift.Geoff Carr for his invaluable scientific key to willows in Australia.Willow identification contacts by state/territory:Note: Some herbaria charge a fee to identify specimens. Please refer to the relevant website or contact the persondirectly to determine costs.17Australian Capital TerritoryPlant Enquiry ServiceAustralian National Botanic GardensGPO Box 1777Canberra ACT 2601Ph: (02) 6250 9540New South WalesBotanical Information ServiceNational Herbarium of NSWBotanic Gardens TrustMrs Macquaries RoadSydney NSW 2000Fax: (02) 9251 1952QueenslandBotanical Information and Advisory ServiceQueensland HerbariumBrisbane Botanic Gardens, Mt Coot-thaMt Coot-tha RdToowong QLD 4066Ph.: (07) 3896 9326 Fax: (07) 3896 9624Queensland.Herbarium@epa.qld.gov.auSouth AustraliaPlant Biodiversity CentrePO Box 2732Kent Town SA 5071Ph: (08) 8222 9307 Fax: (08) 8222 9353TasmaniaMatthew BakerCurator, Weed TaxonomyTasmanian HerbariumPrivate Bag 4Hobart TAS 7001Ph: (03) 6226 1029 Fax: (03) 6226 7865Matthew.Baker@tmag.tas.gov.auVictoriaGeoff CarrDirector, Principal BotanistEcology Australia Pty. Ltd.88b Station StFairfield VIC 3078Ph: (03) 9489 4191 Fax (03) 9481 7679gcarr@ecologyaustralia.com.auIdentifications and Information ServiceRoyal Botanic Gardens MelbournePrivate Bag 2000South YarraVictoria 3141Ph: (03) 9252 2300 Fax: (03) 9252 2442Western AustraliaWestern Australian HerbariumDepartment of Environment and ConservationLocked Bag 104Bentley Delivery Centre WA 6983Ph: (08) 9334 0500 Fax: (08) 9334 0515herbarium@dec.wa.gov.au

Weeds of National SignificanceCompiled by Sarah Holland Clift from:Cremer, K. W. (1995). Willow identification for River Management in Australia. Technical paper No. 3.CSIRO Division of Forestry, Canberra, Australia.Van Kraayenoord, C. W. S., Slui, B. and F. B. Knowles (1995). Introduced Forest Trees in New Zealand:Recognition, role and seed source, 15. The Willows Salix spp. New Zealand Forest Research Institute Limited.Meikle, R. D. (1984). Willows and Poplars of Great Britain and Ireland. Botanical Society of the British Isles,London.18

Specimen informationNumber (year/month/day/sequential number):______________Name:_________________________________________________Date:_ _________________________________________________Precise location (on a map or latitude/longitude or easting/northing):______________________________________________________________________________________________________Town:________________________________ State:___________Growth form (e.g. tree, shrub; weeper, non-weeper):_______________________________________________________Number of trunks (emerging from base):_ _________________Height (m):____________________________________________Bark texture (rough or smooth) & colour:_________________________________________________________________________Colour:fresh stems ____________________________________leaves – upper ____________________________________leaves – under ____________________________________catkins (flowers) ____________________________________roots (if visible) ____________________________________Habitat (e.g. riverbank, wetland, grazed paddock, drainageline, riparian forest etc.):_________________________________________________________________________________________Abundance of mature plants (no./ freq. of plants) andpresence of seedlings:_________________________________________________________________________________________Other info (e.g. damage to tree, growing in stream or alongbank etc.):_____________________________________________________________________________________________________________________________________________________________________________________________________________Specimen informationNumber (year/month/day/sequential number):______________Name:_________________________________________________Date:_ _________________________________________________Precise location (on a map or latitude/longitude or easting/northing):______________________________________________________________________________________________________Town:________________________________ State:___________Growth form (e.g. tree, shrub; weeper, non-weeper):_______________________________________________________Number of trunks (emerging from base):_ _________________Height (m):____________________________________________Bark texture (rough or smooth) & colour:_________________________________________________________________________Colour:fresh stems ____________________________________leaves – upper ____________________________________leaves – under ____________________________________catkins (flowers) ____________________________________roots (if visible) ____________________________________Habitat (e.g. riverbank, wetland, grazed paddock, drainageline, riparian forest etc.):_________________________________________________________________________________________Abundance of mature plants (no./ freq. of plants) andpresence of seedlings:_________________________________________________________________________________________Other info (e.g. damage to tree, growing in stream or alongbank etc.):_____________________________________________________________________________________________________________________________________________________________________________________________________________Specimen informationNumber (year/month/day/sequential number):______________Name:_________________________________________________Date:_ _________________________________________________Precise location (on a map or latitude/longitude or easting/northing):______________________________________________________________________________________________________Town:________________________________ State:___________Growth form (e.g. tree, shrub; weeper, non-weeper):_______________________________________________________Number of trunks (emerging from base):_ _________________Height (m):____________________________________________Bark texture (rough or smooth) & colour:_________________________________________________________________________Colour:fresh stems ____________________________________leaves – upper ____________________________________leaves – under ____________________________________catkins (flowers) ____________________________________roots (if visible) ____________________________________Habitat (e.g. riverbank, wetland, grazed paddock, drainageline, riparian forest etc.):_________________________________________________________________________________________Abundance of mature plants (no./ freq. of plants) andpresence of seedlings:_________________________________________________________________________________________Other info (e.g. damage to tree, growing in stream or alongbank etc.):_____________________________________________________________________________________________________________________________________________________________________________________________________________Specimen informationNumber (year/month/day/sequential number):______________Name:_________________________________________________Date:_ _________________________________________________Precise location (on a map or latitude/longitude or easting/northing):______________________________________________________________________________________________________Town:________________________________ State:___________Growth form (e.g. tree, shrub; weeper, non-weeper):_______________________________________________________Number of trunks (emerging from base):_ _________________Height (m):____________________________________________Bark texture (rough or smooth) & colour:_________________________________________________________________________Colour:fresh stems ____________________________________leaves – upper ____________________________________leaves – under ____________________________________catkins (flowers) ____________________________________roots (if visible) ____________________________________Habitat (e.g. riverbank, wetland, grazed paddock, drainageline, riparian forest etc.):_________________________________________________________________________________________Abundance of mature plants (no./ freq. of plants) andpresence of seedlings:_________________________________________________________________________________________Other info (e.g. damage to tree, growing in stream or alongbank etc.):_____________________________________________________________________________________________________________________________________________________________________________________________________________