Willow Identification Guide (DSE Vic)

Home , Salix babylonica, Salix fragilis, Salix nigra

December, 1998 Willow identification guide LC0117 Compiled by the Albury/Wodonga Willow Management Working Group ISSN 1329-833X

This Landcare Note is a guide to identifying the watercourses: an introduction. It is important to manage frequently occurring willows in North East Victoria. willows to minimise environmental damage. More details to aid identification are given in Cremer Appropriate management will vary depending on the local (1995). situation and type of willow, but is likely to include gradual removal of some willows and preferential planting Introduction of local native or indigenous species along watercourses. Willows are exotic plants originally introduced to Planting willows should be a last erosion-control resort Australia for stabilising watercourses and road fills, as only and include planning for their staged removal once ornamentals, for providing shelter and producing baskets back-up indigenous plants have established. and cricket bats. There are over one hundred introduced willow species, varieties, cultivars and hybrids in The need for willow identification Australia. Many of these have potential to cause stream Proper identification (type and sex) is necessary for management problems, and reduce watercourse willows to be managed effectively. Each willow plant is environmental values. In North East Victoria there are either male or female, and if plants of both sexes are around a dozen types of willow that occur frequently, and present in a locality, pollination can result. It is therefore about eight of these have potential to cause management important to know the sex of willows, as an indication of problems. their ability to spread from seed. The sex can be determined during spring by examining the flower. How willows spread If you are uncertain of the identity of a willow or willows, Willows can spread prolifically from broken twigs taking collect specimens of branches with flowers and leaves for root downstream. The most widespread willows are examination by someone more experienced (refer to characterised by brittle branches which are easily broken, section “Further information” at the end of this Note). providing material for vegetative spread. The willow’s ability to grow in continuously wet situations means that it Identifying Willows can encroach into the centre of watercourses, as well as Key features to look for when identifying willows are: spreading along the banks. Branches broken off to use to 1. Flowers. The flower shape, size, number of flower anchor fishing lines are another cause of willow spread. parts, sex and flowering time. Willows can also reproduce prolifically from seed, 2. Form. Trees or shrubs; narrow or wide crowns; single- producing seedlings resulting from cross-pollination stemmed or multi-stemmed; weeping, contorted or between different types. Hybrids, resulting from upright branches. interbreeding between different hybrids or cultivars, are still being identified in the North East. Willows can 3. Leaves. The leaf shape, size, colour, degree of germinate in massive numbers (half a million seedlings hairiness, edge shape and number of veins. were recorded at one site), and form islands in 4. Bark. The bark colour and texture. watercourses. 5. Branches. The degree of brittleness or rigidity (ie. do they snap when broken?). The need for willow management 6. Roots. The Colour of exposed roots, pink or white As willows are able to spread prolifically along depending on taxon. watercourses, there is significant potential for willows to dominate riparian vegetation. Indeed, many watercourses Note that while the above features are used to distinguish and swamps have been invaded and are already dominated different willow species and hybrids, the willow’s sex can by willows. If such spread is left to take its course, only be determined during the flowering season, during significant adverse environmental impacts are inevitable, spring. as outlined in Landcare Note LC0118: Willows along

Frequently occurring willows in north east Victoria Species Appearance Description Management Crack willow Tall, multi-stemmed tree with rounded or If female trees of other (or basket willow) irregular crown. Fragile twigs, which willows are in the break with a ‘crack’, and blow off in vicinity (eg. up to 400 Salix fragilis var. strong wind. Leaves long with a toothed m) they should be fragilis & S. fragilis outer edge. Conspicuous glands at base of removed to prevent var. furcata. leaf stalk. Most commonly planted willow interbreeding, in north east Victoria, and has since spread particularly if they are along banks and in mid-stream gravel bars. Salix alba varieties. Spreads vegetatively, by broken twigs and Needs long-term branches taking root. Only male plants maintenance to reduce present in Australia. vegetative spread.

Gold-crack willow/ Tree up to 16 m high with rounded or A very serious basket willow spreading crown and many stems (which environmental weed. are sometimes low branches partially Female trees need to be buried under silt). Narrow leaves with removed. Male trees Salix × rubens finely toothed margins. Bark from gold to should be continually grey-green. Branches extremely fragile maintained through and easily broken off in storms and floods lopping to minimise (with potential to take root downstream). risk of spread. Both male and females present in Australia. The most widespread and abundant type of willow regenerating from seed in Australian rivers, and very widespread and common in Victoria. Weeping willow Single-trunked tree with weeping form. Expected to produce Salix babylonica Crown often more wide than high. Long fertile hybrids.Check narrow leaves. Holds its leaves longer than for seed production other willows. Has spread vegetatively. before planting any Only female plants in Australia. weeping willow, because not all ‘weeping willows’ are true Salix babylonica (some are fertile S. babylonica hybrids).

Tortured willow Tree about 14 m high with short single Has already hybridised Salix matsudana trunk or up to 4 stems, and strongly in Australia with at ‘tortuosa’ contorted weeping branches. Commonly least 4 other taxa/ planted as ornamental. Has spread in parts hybrids. Needs to be of Victoria and NSW. Only female plants carefully managed. present in Australia. Overseas it crosses with other willows (such as crack willow/ Salix fragilis & matsudana willow/ Salix matsudana × alba to produce fertile hybrids.

Species Appearance Description Management Golden willow/ Spreading tree to about 15 m high. Hybridises with any golden upright Conspicuous by golden coloured twigs other member of willow (or basket and branches. Only female plants present subgenus Salix. Needs willow) in Australia. Interbreeds with crack careful management. Salix alba var. willow/ Salix fragilis, producing fertile vitellina hybrids of both sexes of Salix × rubens. Common source of seedlings in rivers.

Black willow Large upright tree, usually single- Has hybridised with S. Salix nigra stemmed. Conical when young, becoming fragilis var. fragilis in broader with age. Deeply fissured, rough ACT, and probably bark. Long thin leaves, almost equally others elsewhere. green on both sides. Shiny red brown Needs controlling. twigs. Grows fast. Reproduces from seed and vegetatively. Produces large quantities of seed which disperse over wide areas germinating in moist soil, including table drains. Both male and female plants in Australia. Spreading aggressively in North East Victoria in Kiewa and Ovens catchments. Likely to hybridise with other Willow species.

New Zealand hybrid Single-stemmed tree with narrow crown. Do not plant female willows Long, thin leaves with toothed edges. trees. Do not plant Salix matsudana × S. Often thought to be a cross between a male trees within 1 km alba hybrids willow and poplar. Fast-growing. Planted of weeping willows. for off-stream farm purposes such as windbreaks. Both male and female trees in Australia. Breeds with stream-side willows (such as weeping willow/ Salix babylonica) which then produce seed, leading to further downstream spread.

Frequently occurring willows in north east Victoria (continued) Species Appearance Description Management Purple osier Shrub or small multi-stemmed tree willow Needs careful Salix purpurea up to 6 m high, with many ascending management as its stems. Crown rounded or spreading. populations are Leaves thin textured, dark green above and expected to expand. paler beneath. Both males and females in Australia. Vegetative reproduction is limited, but abundant seed has been set in some locations.

Pussy willow/ grey Shrub or small multi-stemmed tree with Do not plant female sallow/ grey willow several sturdy branches arising near trees. Needs careful Salix cinerea ground-level. Rounded crown. Wood management. ridged under bark. Broad, variable leaves, hairy both sides, with toothed or wavy edges. Reproduces mainly by seed (which is abundant). Occurs along streams or near seasonal to permanent bogs and swamps. Female trees present. Widespread in Ovens and King catchments. Invasive in both disturbed and undisturbed situations, and is spreading aggressively.

Weeping willow Diagram unavailable at this Large spreading tree to 18 m high with Potential to spread Salix × sepulcralis stage. long pendulous branches. Branches var. sepulcralis moderately brittle. Reproduces from seed and vegetatively. Previously identified as S. babylonica.

Golden weeping Large spreading tree to 18 m high with Strong potential to willow long pendulous branches. Spread is mainly spread. Serious threat. S. sepulcralis var. by vegetative means. Isolated trees can set chrysocoma viable seed, due to flowers of both sexes in catkins.

Further information and action Acknowledgements Before any willow removal works are undertaken, the This Landcare Note is a compilation of material from River Management Group of the Catchment Management Cremer (1995); Carr (1996) and Thexton (1996). Authority must be consulted. These Landcare Notes on The Working Group thank Geoff Carr - Ecology Australia, willows are provided as a guide only, and should be used Ed Thexton - Riparian Australia and Ross Hardy - ID&A, in conjunction with on-ground advice from any of the for their comments. following: • Catchment Management Authority (the River The Albury/Wodonga Willow Management Working Management Group) Group consists of: Clare Purtle, DLWC, Albury; Fleur • Stelling, NRE Wodonga; Denis Martin, Greening Department of Natural Resources and Environment, Australia, Beechworth; Terry Grossman, Goulburn Broken Victoria CMA; Judy Frankenberg, CFM Consulting; Susan • Greening Australia Campbell, CFM Consulting, and Chris Dwyer, ID & A • National Herbarium. Royal Botanic Gardens, Pty. Ltd. Wangaratta. Melbourne. • Environmental Consultants. This publication may be of assistance to you but the State of Victoria and its officers do not guarantee that the publication is without flaw See the following related Landcare Notes: of any kind or is wholly appropriate for your particular purposes LC0118: Willows along watercourses: an and therefore disclaims all liability for any error, loss or other introduction consequence which may arise from you relying on any information in this publication. LC0119: Willows along watercourses: their impact compared to natives LC0120: Watercourse revegetation using indigenous plants LC0121: Willows along watercourses: managing, removing and replacing

References Carr, G.W. (1996) Salix in ‘Flora of Victoria’ Vol. 3. Eds. Walsh, N.G. and Entwisle, T.J. Inkata Press. Melbourne. Cremer, K.W. (1995) ‘Willow Identification for River Management in Australia’. CSIRO Division of Forestry. Ladson, A., Gerrish, G., Carr, G. & Thexton, E. (1997) ‘Willows Along Victorian Waterways. Towards a Management Strategy’. Waterways Unit. Department of Natural Resources and Environment. Thexton, E. (1990) Ovens River Catchment Streamside Revegetation Strategy, Part A Background Information. Ovens River Management Board, Wangaratta.