Section 1. Biology and Threat - Weeds Australia

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Section 1. Biology and Threat - Weeds Australia

Section 1Biology and threatUnderstanding asparagus weeds 2Which Asparagus species are weeds in Australia? 2Naming asparagus weeds – scientific vs. common names 2How did they become weeds? 3What do they look like? 3What‘s going on underground? 4Identifying asparagus weeds 6Distinguishing between five asparagus weed species and Australia’snative asparagus 6Distinguishing between common and Western Cape bridal creeper 8Where to find asparagus weeds 10How do they spread? 10Where do they grow? 10What impacts do they cause? 10Biology, ecology and impacts of asparagus weeds in Australia 11Asparagus aethiopicus 11Asparagus africanus 13Asparagus plumosus 15Asparagus scandens 17Asparagus declinatus 19The two forms of bridal creeper (Asparagus asparagoides) 21New and emerging asparagus weeds 26Other non-native Asparagus species to look out for and eradicate 281


How did they become weeds?The asparagus weeds listed as WoNS wereintroduced to Australia from southern andeastern Africa in the mid to late 1800s mainly forornamental purposes such as hanging baskets andgarden plants. Indeed, A. aethiopicus is commonlyknown as basket asparagus, and the flowersand foliage of A. declinatus (bridal veil) and A.asparagoides (bridal creeper) were commonly usedin weddings. While the weedy asparagus speciesare no longer traded commercially, several speciesare still likely to be traded among home gardenersand many are still extremely common in gardens.Due to their ability to easily disperse and establishin many environments, asparagus weeds havespread from gardens into native bushland wherethey cause major negative impacts.Management note: Asparagus weedscan be difficult to control because: a)they generally have large undergroundreserves, and b) several species have fineor waxy foliage that impede herbicideuptake. After control, active restorationmay be necessary because root mats canpersist and continue to cause impacts longafter plants have been killed. Any newoutbreaks should be quickly controlled toensure extensive root mats do not develop.What do they look like?Above groundMost asparagus weeds have wiry, twining stemsthat can clamber over native vegetation. Somespecies (e.g. A. aethiopicus and A. africanus)have sharp spines along these stems. True leavesare reduced to small bracts or scales, while thebranches are modified into leaf-like structuresknown as cladodes. The cladodes (leaves) varyamong species, from very fine and needle-like (e.g.A. declinatus) to wide, thick leaf-like structures(e.g. A. asparagoides). The above ground foliageNeedle-like ‘leaves’ of A. declinatus compared to thick ‘leaves’ ofA. asparagoidesmay either dry off each summer or stay aliveyear round, depending on the species or climaticconditions. For example, the above ground foliageof A. declinatus and both forms of bridal creepergenerally dies back each summer and re-sprouts thefollowing autumn but, in cool, moist conditions,some plants may retain foliage all year.Asparagus weeds have small, white or creamcoloured flowers. They form fleshy berries that varyin colour depending on the species. Floweringand fruiting times can vary greatly with climateand location. The asparagus weeds described inthis manual are bisexual, meaning that the male(stamens) and female (pistils) parts are containedwithin each flower.Below groundAll asparagus weeds can form large root masses(rhizomatous roots), which persist year round andcan be up to 85% of the plant’s biomass. Thisallows the weeds to withstand harsh conditions,including drought and fire.Some species form ‘crowns’ at the base of thestems, with a root mass radiating out from thecrown. Other species form extensive root matsjust under the soil surface. Asparagus roots oftenhave many large tubers that act as storage organsto provide plants with nutrients and moisture (seepages 4 and 5 for root description).Management note: It is important to knowwhat is going on underground in order toplan your management and select the mosteffective control techniques.Shauna Potter3


Biology and threatIdentifying asparagus weedsDistinguishing between five asparagus weeds and Australia’s native asparagusSpecies A. aethiopicus (ground asparagus) A. declinatus (bridal veil) A. scandens (asparagus fern)HabitPerennial, lowgrowing herb withsprawling or archingstems arising froma crownHillary CherryCreeping or climbingplant up to 3 m tallwith annual twiningstems and perennialrhizomes and tubersShauna PotterPerennial, lowgrowing herb withtwining stems up to3 m highMatt SheehanCladodes(leaves)and stemsFlattened withdistinct midrib; singleor clustered (2–5),up to 20 mm long; nohairs; pale greenStems up to 2 m long;green to brown,rounded but ridgedalong length, withmany small branchesand short sharpspinesNeedle-like, soft,greyish-green orbluish-green; ingroups of 3 alongstem, up to 20 mmlongStems with manyside branches thatbear cladodesgiving a fern-likeappearance. Stemssmooth (no thorns)Lance-shaped, flatwith distinct midrib,in groups of 3 anddeep green, 5–15mm long and 0.5–1mm wideStems branch in oneflat plane. Stemssmooth (no thorns)Glen Sanders Shauna Potter Glen SandersFlowersCreamy whiteto pale pink inelongated clustersof 4–8Greenish white;solitary or in pairs;on short stalksWhite to pinkishwhite;solitary or2–3 per axil on shortstalksRos Shepherd Glen Sanders Murray FaggFruits Glossy berries 5–8mm in diameter;initially greenturning brightred when mature;contain a singleblack seed 3–4 mmin diameterSpherical or ovoidberry 8–15 mm indiameter; initiallygreen turning palebluish-grey orwhitish-translucentwhen mature;contain 2–14 blackseedsFleshy, globularberries 5–7 mmdiameter; initiallygreen turning toorange-red whenmature; contain oneblack seedHillary Cherry Colin Wilson Shauna PotterRootsDense mat ofundergroundstems (rhizomes)and fleshy tubersscattered alongroots; stems arisefrom a central crownDense mat of fibrousrhizomes, withclusters of thickbulb-like ribbedtubers to 6 cm long;stems arise from thelength of rhizomesShort rhizomes withfibrous roots, oftenwith narrow tubers;stems arise from asmall central crownHillary Cherry Kerinne Harvey Biosecurity SA6


Species A. plumosus (climbing asparagus fern) A. africanus (climbing asparagus) A. racemosus (native asparagus)HabitPerennial climberwith stems 5 m ormore in lengthPerennial climberwith stems up to5 m longA slender, shrub orclimbing, perennialvine that can growup to 4 m longIan HuttonHillary CherrySheldon NavieCladodes(leaves)and stemsNeedle-shaped, fineand thread-like inclusters of ten ormore; to 7 mm long,0.5 mm wideStems, green to redbrown,spinelessor with scatteredspines; with twiningbranches in aflattened planeSheldon NavieSpine-like andcylindrical; inclusters of 6–12, upto 15 mm long; withsharp tips; appearsfern-likeStems hairless, oftenbearing thorns orspines 2–10 mmlong; twining andbecome woody andthick with ageHillary CherrySpine-like andlinear; in clustersof 3–6; 10–30 mmlong, 0.2–0.5 mmwideStems slender to2 cm in diameter;with some curvedspines 1–5 mm longSheldon NavieFlowersGreenish-white; single or paired in axils,along lateral branchesGreenish-white;solitary or in clustersof up to 6, on shortstalksMinute, white flowers on short, spiky stems;single or paired, 4–6 mm in diameterSheldon NavieFruits Globular berry 4–5mm in diameter;initially greenturning bluishblackto black withmaturity; contain1–3 black seedsGlobular berry 5–6mm in diameter;initially greenturning orange-redand shrivelled withmaturity; contain ablack single seedGlobular berry 5–6 mm in diameter; redwhen mature; contain a single black seedSheldon NavieSheldon NavieRootsFibrous and fleshy,root swelling butwithout distincttubers; with shortrhizomes; stemsarise from a centralcrownHillary CherryFibrous, fleshy, rootswelling but withoutdistinct tubers; withshort rhizomes;stems arise from acentral crownHillary CherryFibrous with long tubers7


Biology and threatWhere to find asparagus weedsHow do they spread?Asparagus weeds are mainly spread by birds andother animals, or by water. They reproduce mostlyby seed and many species reach reproductivematurity within the first two years. They can spreadlong distances as they produce large amounts offleshy fruit that is readily dispersed by birds andsome mammals.Asparagus weeds can also spread vegetatively byrhizomes. They are spread by humans, who stillplant them, transport them unintentionally withmachinery or dump them in garden waste. Theyalso often re-sprout following control efforts, sofollow-up management is critical.Where do they grow?Asparagus weeds tolerate a wide range of soilsand climates. Most prefer shady, moist conditions,but they can withstand full sun, drought andimpoverished soils. Some asparagus weeds, suchas Western Cape bridal creeper, A. scandens andA. declinatus, can tolerate cold winters and frost.Other species, such as A. plumosus, successfullyinvade both sub-tropical and temperate regions (seemaps on pages 11–21).What impacts do they cause?Asparagus weed infestations expand quickly dueto the rapid growth of root systems, even underharsh conditions, and can form monocultures anddisplace native plants. Above ground biomass may:• dominate the ground and shrub layer (e.g.A. aethiopicus, A. scandens, A. declinatus,Western Cape bridal creeper and commonbridal creeper) and/or the canopy layer (e.g.A. africanus, A. plumosus),• restrict movement of some native animals andthereby reduce their access to food and dens,• provide harbour for exotic animals, such asfoxes and rabbits, and• alter rates of litter decomposition and nutrientcycling, due to the large amount of foliage shedby some asparagus weeds each summer.Below the ground, the often impenetrable root matscan:• impede the growth of native seedlings,• alter the composition and ultimately reduce thediversity of organisms in the soil and litter, and• compete for water and nutrients with native plants.Due to their impacts,asparagus weeds are listedas a Key Threatening Process(KTP) under the EnvironmentProtection and BiodiversityConservation Act 1999 (EPBCAct) within the category:‘Loss and degradation of nativeplant and animal habitat byinvasion of escaped gardenplants, including aquaticplants’.Paul Lennon10


Biology, ecology and impactsof asparagus weeds in AustraliaAsparagus aethiopicusAsparagus aethiopicus is predominantly knownas ground asparagus but other common namesinclude basket asparagus, asparagus fern,Sprengeri’s fern, bush asparagus and emeraldasparagus. It was previously known as A.densiflorus ‘Myers’ in Australia, but this is nowconsidered to be a different species not knownto be recorded in Australia (Navie and Adkins2008). Asparagus aethiopicus has also beenknown as Protasparagus aethiopicus (L.) Oberm.and P. densiflorus (Kunth) Oberm. Cultivars of A.aethiopicus also exist and include ‘Sprengeri’,‘Meyersii’ and ‘Variegata’. The cultivar ‘Sprengeri’is considered to be the invasive form of A.aethiopicus throughout Queensland (QLD). Theother cultivars are not known to be naturalised inAustralia. More research is required to determinewhat forms may have naturalised in Australia, andwhether cultivars are sterile.! Asparagus aethiopicus! Asparagus aethiopicusUnsuitableMarginally suitableModerately suitableUnsuitableMarginally suitableModerately suitableHighly suitableHighly suitableNRM BoundaryNRM BoundaryCurrent and potential distribution (Scott and Batchelor 2006)of Asparagus aethiopicuslocations. While frost may damage the foliage,plants are quick to recover from the rhizomes.Asparagus aethiopicus occurs in a vast range ofnative habitats, including coastal headlands andsandy foredunes, littoral rainforests, heathlands,open woodlands, riparian areas and wetlandsincluding estuarine edges, salt marshes andswamps. It can grow in the forks of trees, in birdsnest ferns and amongst rocks or leaf-litter.Environmental impactsLord HoweIslandOrigin and distributionAsparagus aethiopicus was introduced to Australiafrom the Cape Province of South Africa and hasbeen cultivated extensively as an ornamental plant.It has since escaped from gardens to become amajor environmental weed in the south and eastof Australia (including Lord Howe Island where itwas introduced during the 1930s), New Zealand,Hawaii, Caribbean, Europe, parts of North America.Climate modelling indicates that A. aethiopicushas the potential to spread more widely in coastalQLD, and infill coastal areas in New South Wales(NSW) (Scott and Batchelor 2006).Habitat in AustraliaAsparagus aethiopicus occurs in warm coastalregions with rainfall from 500–1500 mm. It isdrought tolerant and can survive in hot, dryAsparagus aethiopicus creates vigorous thickets offoliage that forms dense spiny mats. It can quicklyinvade disturbed sites in open sun or partial shade.Plants can form monocultures that smother anddisplace native herbs and shrubs, and can formimpenetrable root mats below the ground that mayimpede the growth of native seedlings. The aboveground biomass can dominate the native groundand shrub layer. Large amounts of below groundbiomass may allow the weed to persist in harshconditions, while enabling strong competition withnative species.In south-eastern QLD, A. aethiopicus is rankedamong the top 25 most invasive plant species andit is one of the most significant garden escapesinvading coastal habitats (Batianoff and Butler2002). In NSW, it is ranked 4th among 340 of theworst environmental weeds, based on its threat andimpact on biodiversity (Downey et al. 2010).11


Biology and threatBiology and ecologyAsparagus aethiopicus is a low growing scramblerwith prostrate, prickly stems that grow up to2 m long, and arise from a central undergroundcrown (cluster of short rhizomes; see page 4). Thecladodes (leaves) are flattened and lance-shaped,growing in clusters of 2–5. Plants are perennial,retaining above ground foliage year round. Small,watery tubers form along the roots and act asstorage organs, but these tubers are not capable ofvegetative reproduction.Foredune invasion of Asparagus aethiopicus, Coffs Harbour, NSWHillary CherrySpread is primarily by seed, but vegetative growthalso occurs from the short rhizomes that comprisethe central crown. Reproductive maturity occurswithin the first two years, with staggered floweringoccurring across plants from spring to autumn.Timings vary with climatic conditions and soilmoisture. Peak fruit production occurs from autumnto winter, but plants may flower and fruit yearround in favourable conditions. Seedlings cangerminate at any time if water is available, buttypically there is a major flush of germination inspring and a smaller one in autumn. Germinationrates are higher than several other asparagus weeds(>98%), with a high mean seedling emergence(94.5%) (Vivian-Smith and Gosper 2010).Although seed dormancy is rare, some seedsmay survive for three or more years in the soil.Experiments have shown that seedlings can emergefor up to 1000 days after sowing (Vivian-Smith andGosper 2010). Seeds are also viable while the fruitis still immature (i.e. green). Plants mature early(approx 1.5 years) and produce large numbers offlowering stems (average of 60 per plant) (Vivian-Smith and Gosper 2010). Under favourableenvironmental conditions, mature plants canAsparagus aethiopicus fruits and foliageproduce a large amount of fruit (up to 600 maturefruits observed on one plant; Bowden and Rogers1996).The fruits are relatively large (to 9 mm), attractiveand bright red when ripe and have a high mineralcontent that makes them desirable to animals. It isreadily dispersed by birds and lizards. Birds helpdisperse the fruits long distances depositing them inundisturbed vegetation, where they can germinateand grow. Asparagus aethiopicus is also dispersedby humans, who spread rhizomes and fruits indumped garden waste.These characteristics provide considerablemanagement challenges, such as dealing withrapid germination and emergence following birddispersal to non-infested sites and its robust,underground storage capacity. In contrast,managers do not need to contend with a long-livedseed bank due to low dormancy in this species.Hillary CherrySeasonal patterns for Asparagus aethiopicusSummer Autumn Winter SpringDec Jan Feb Mar Apr May Jun Jul Aug Sep Oct NovFloweringFruitingGerminationGenerally presentPresent in suitableconditions12


Asparagus africanusAsparagus africanus is most commonly known asclimbing asparagus, but is also known as asparagusfern or ornamental asparagus. It was previouslycalled Protasparagus africanus (Lam.) Oberm.Origin and distributionAsparagus africanus was introduced to Australiaas a garden ornamental from southern Africa andhas escaped from cultivation to become a majorweed of natural vegetation. The earliest naturalisedspecimens were collected from the Ipswich area,west of Brisbane in the 1940s. The distribution ofA. africanus extends from central west QLD andalong the coast from northern QLD to central NSW.It is particularly common in coastal districts nearsettlements.Climate modelling indicates that A. africanus couldexpand its range in coastal regions from far northQLD to southern VIC, as well as coastal areas of SAand south-west Western Australia (WA), althoughthere is low confidence in the current model andfurther work should be done (Scott and Batchelor2006).Habitat in AustraliaAsparagus africanus occurs in a range of habitats,but is primarily a weed of sub-tropical to tropicalforests, rainforest margins, littoral rainforests,hind dunes, open woodlands, riparian corridors,mangroves, brigalow scrub (Acacia harpophylla)and wet eucalypt forests. It also invades urbanbushland and roadsides and is commonly foundin ecotone areas (the transition area between twoplant communities), disturbed bushland, parks andgardens. It is moderately tolerant to drought stress.Environmental impactsAsparagus africanus grows quickly and producesdense thickets of foliage that can climb anddominate the canopy layer, smother native herbsand shrubs and form monocultures, which in turncan alter the functioning of the native ecosystem.#Asparagus africanusNRM BoundaryNo Reported OccurrenceCurrent distribution of Asparagus africanusInfestations are quick to expand, as the welldeveloped root system enables rapid growth,even under harsh conditions such as drought orimpoverished soils. The fibrous roots form densemats just below the soil surface that may interferewith the germination and seedling survival of nativeplants (Navie and Adkins 2008).In south-eastern QLD, A. africanus is ranked amongthe top ten most invasive plants, and extensiveinfestations of A. africanus threaten remnantbrigalow scrub (Batianoff and Butler 2002) whichis listed (Brigalow – Acacia harpophylla dominantand co-dominant) as an endangered ecologicalcommunity under the EPBC Act.Biology and ecologyAsparagus africanus is a long-lived climber orscrambling sub-shrub that can form woody stems.The stems grow in a twining fashion and developlarge, sharp spines. Stems originate from a basalcrown (up to 60 cm in diameter) consisting ofshort, fleshy rhizomes (see page 4 for root and stemstructure). Plants are perennial, retaining aboveground foliage year round. Unlike A. aethiopicus,the roots do not form distinct tubers but develop13


Biology and threatthick swellings along the root structure. The rootmass is thick and forms a fibrous mat below thesoil.Mature A. africanus plants can produce as manyas 21,000 seeds per year and immature fruits cancontain viable seed (Stanley 1994). In cultivation,plants reach reproductive maturity at 3–4 yearsof age (Vivian-Smith and Gosper 2010), but fieldobservations indicate reproductive maturity canoccur within 1–2 years. Seed survival is typicallyup to three years in the soil, but under favourableenvironmental conditions, seeds can survive longer(Stanley 1994). The round fruit contains a singleseed (occasionally two) and fruit production peaksin summer, but fruit can often remain on the plantthroughout the year. The fruit turns from green toorange to orange-red as it matures.Asparagus africanus is readily dispersed by manybirds, including silvereyes (Zosterops lateralis) andsouthern figbirds (Sphecotheres viridis vieilloti), butis also spread from rhizomes in dumped gardenwaste (Stanley 1994).Invasion of Asparagus africanus, Tinchi Tamba Wetlands, BrisbaneKerinne HarveyThe only Asparagus speciesthat is native to Australia isA. racemosus and itsdistribution overlaps with bothA. africanus and A. plumosus.Clear identification between the nativeand weedy asparagus species is imperative.See pages 7, 8 and 43 for photos andinformation on A. racemosus.Asparagus africanus fruits and foliageSheldon NavieSeasonal patterns for Asparagus africanusFloweringFruitingGerminationSummer Autumn Winter SpringDec Jan Feb Mar Apr May Jun Jul Aug Sep Oct NovGenerally presentPresent in suitableconditions14


Asparagus plumosusAsparagus plumosus is most commonly known asclimbing asparagus fern, but is also known asferny asparagus. Previous scientific nameshave included A. plumosus var. nanusHort. and Protasparagus plumosus (Baker)Oberm. It has been incorrectly calledA. setaceus (Kunth) Jessop.Origin and distributionAsparagus plumosus is a native ofsouthern and eastern Africa (Kenya, Zambiaand South Africa), but is often cultivatedelsewhere as an ornamental plant and commonlyused in floral arrangements. It has naturalisedin the southern United States of America (USA)(California and Florida), Puerto Rico and somePacific Islands (Hawaii and Tonga). In Australia, itis mainly found in southern and eastern coastalregions, predominantly near major urban areassuch as Brisbane, Sydney and Adelaide. It is alsonaturalised in other parts of NSW, south-west WA,southern VIC, north and central QLD, Lord HoweIsland and Norfolk Island.Climate modelling indicates that it is a potentialthreat to coastal regions of QLD, potentiallyextending north to Cape York, although there is lowconfidence in the current model and further workshould be done (Scott and Batchelor 2006).Habitat in AustraliaAsparagus plumosus is found in fertile soils oftropical, sub-tropical and warm temperate regionrainforests, littoral rainforests, Casuarina forests,forest margins, riparian areas, hind dune forests,urban bushland and open woodlands, generally inareas of 500–1500 mm annual rainfall. Asparagusplumosus tolerates low light and moist conditions,allowing it to invade rainforests. It also toleratessandy soils and saline environments, such assaltmarsh communities. It is commonly foundalong roadsides and in disturbed sites, parks and! Asparagus plumosusNRM BoundaryNo Reported OccurrenceCurrent distribution of Asparagus plumosusgardens. Infestations are often isolated and may bethe result of rhizomes spread by garden dumpingrather than from seed.Environmental impactsLord HoweIslandAsparagus plumosus has the potential tosignificantly alter habitats by dominating anddestroying the canopy layer. It can produce largerhizome clusters (crowns) that penetrate deeperinto the soil as they grow, making them especiallydifficult to dig out. These large underground crownsand root systems may alter native regeneration.On Lord Howe Island, invasion of A. plumosusis potentially impacting the native habitat of theendangered woodhen (Gallirallus sylvestris).Asparagus plumosus is ranked among the top60 most invasive environmental weeds in southeastQLD (Batianoff and Butler 2002), where itis a particular concern in dry rainforests (Navieand Adkins 2008). It was also ranked among thetop twenty environmental weeds during a surveyconducted on the North Coast region of NSW(Navie and Adkins 2008).15


Biology and threatBiology and ecologyAsparagus plumosus is a twining vine, with greento reddish-brown stems that become woody withage. Stems may have small, sharp recurved spines.Plants are perennial, retaining above ground foliageyear round. The fibrous and fleshy roots branchfrom a rhizomatous crown at the base of stems. Theroots do not form distinct tubers but may thickenalong the root structure. The branches are arrangedin a flat plane and have whorls of tiny, fine roundedcladodes, arranged in tight clusters of 8–15 perwhorl, giving the plant a feathery appearance.The flowers are small and greenish-white and occursingly or in pairs on branchlet tips. Flowers areproduced from spring through to early autumn, butplants may not flower in the first year. Reproductivematurity generally occurs after two years and up tofour years depending upon light availability. Fruitsare black, fleshy berries that ripen from autumn towinter. Seeds germinate from autumn to spring andseedlings develop rapidly.Seeds are primarily dispersed by birds, but are alsospread in water and plants can spread vegetativelyby rhizomes in garden refuse.Invasion of Asparagus plumosus, Lord Howe IslandAsparagus plumosus fruits and foliageIan HuttonSheldon NavierhizomeDrawing by Catherine Wardrop ©Royal Botanic Gardens and Domain TrustSheldon NavieAsparagus plumosus rhizomeA. plumosus (left) with shorter, finer cladodes and A. africanus (right)Seasonal patterns for Asparagus plumosusFloweringFruitingGerminationSummer Autumn Winter SpringDec Jan Feb Mar Apr May Jun Jul Aug Sep Oct NovGenerally presentPresent in suitableconditions16


Asparagus scandensAsparagus scandens is commonly known asasparagus fern, but is also known as climbingasparagus, climbing fern and snakefeather. Theprevious scientific name was Myrsiphyllumscandens (Thunb.) Oberm.Origin and distributionAsparagus scandens was introduced as a gardenornamental from southern Africa. Infestations arewidely scattered within Australia but are increasing,particularly in southern VIC. Infestations also occurin northern Tasmania (TAS), SA (with emergingpopulations in the Adelaide Hills), around Sydney,and isolated infestations in south-west WA, nearDenmark and Albany. At least 15 years ago,A. scandens was rampant on Lord Howe Island,but it is currently being controlled. It has alsonaturalised in New Zealand and Central America.The distribution of A. scandens predominantlyoccurs in areas close to human habitation inAustralia. But its invasive ability in climaticallysimilar habitats of New Zealand suggests that A.scandens could seriously impact on Australia’sbiodiversity if not controlled.Bioclimatic modelling indicates that A. scandensmay spread north in coastal areas of central andsouthern QLD and expand across coastal regions ofNSW, SA, TAS, VIC and south-west WA (Scott andBatchelor 2006).Habitat in AustraliaAsparagus scandens generally occurs in subtropicalto temperate, high rainfall regions. Itinvades shaded woodland, heathland, sclerophyllforest, cool temperate rainforest, riparian andcoastal habitats, and disturbed areas. Generallyit is found in shady areas, but plants can alsoestablish under moderate light. Plants appearto need moisture all year round and favourriparian habitats, but they can tolerate a range ofconditions, from open sites to deep shade andXAsparagus scandensNRM BoundaryNo Reported OccurrenceCurrent distribution of Asparagus scandensdamp to dry forest. Asparagus scandens is tolerantof fire and drought and may tolerate frosts. OnFlinders Island (TAS) in Bass Strait, it has invadednative riparian habitats. In south-west WA, aroundDenmark and Albany, infestations occur in Agonisand Banksia woodlands and riparian areas.Environmental impactsAsparagus scandens is a serious environmentalweed threat to southern Australia. It is shadetolerant and competes with native plants for water,nutrients and space. The tuberous root systemcan form dense mats that impede native seedlinggermination, and the twining stems strangle orsmother small seedlings and shrubs.In New Zealand (NZ), it is the most damagingand widespread of all asparagus weeds. It canstrangle or smother soft-barked plants and preventthe regeneration of native plants. On the NorthIsland of NZ, A. scandens invades extensive areasof lowland broad-leaved and secondary forests.Following control of large infestations, the largeamount of dead root biomass appears to impedethe growth of other plants until the root massdecomposes (Timmins and Reid 2000).In Australia, there is speculation that A. scandensmay cause impacts on biodiversity similar to thosecaused by common bridal creeper (Lawrie 2004).17


Biology and threatMovement by humans is a major cause of spread.As a result, infestations are commonly found neartowns. However, because A. scandens is bothshade-tolerant and bird-dispersed, it can invadeintact as well as disturbed native forest. Thusseedlings can be hard to find and areas need to bethoroughly searched to enable control (Timminsand Reid 2000). It can also grow as an epiphyte ontree ferns and in tree branch crooks.Biology and ecologyAsparagus scandens is a creeping or climbing vinewith thornless, wiry stems. Plants are perennial,and generally retain above ground foliage yearround. The green, delicately-branching stems,that give the plant a fern-like appearance, arisefrom a crown at the base of stems. The dark greencladodes (leaves) are linear and often slightlycurved (sickle-shaped). They occur in groups ofthree along fine branchlets.Fibrous underground roots form small thin tubersthat are predominantly for water storage. The rootsystem can constitute up to 87–92% of matureplant biomass, allowing the plant to be extremelyfire, drought and shade tolerant (Timmins and Reid2000).The fruit is a glossy, globe-shaped berry that ripensto orange-red when mature and usually containsone seed. Fruit appear in late spring and canremain on the plant until the following floweringseason in wet years. An average of 64 fruit has beenfound on 1 m lengths of fruiting stems (Timminsand Reid 2000).Invasion of Asparagus scandensAsparagus scandens fruits and foliageReproductive maturity can occur after 12 months.Seedlings germinate from spring through tosummer. The seeds are dispersed by birds and arelikely dispersed by foxes and rabbits. Asparagusscandens is also spread by water and earth movingmachinery, mud caught on vehicles and shoes,rhizomes in garden refuse and plant exchangethrough gardeners.Denmark Weed Action GroupShauna PotterSeasonal patterns for Asparagus scandensFloweringFruitingGerminationFoliage presentSummer Autumn Winter SpringDec Jan Feb Mar Apr May Jun Jul Aug Sep Oct NovGenerally presentPresent in suitableconditions18


Biology and threatColin Wilson; Hilary Cherry (inset)Tim ParkinsonAsparagus declinatus fruits and foliage (inset: fruit and seeds)Invasion of Asparagus declinatus, Newland Hill, South Australiaduring the summer and reappears with autumnrains, but in cool and wet areas fruit can stay onthe plant through summer. There is little knowledgeabout its growth rate but it may be similar to bridalcreeper.Underground rhizomes radiate from the base ofstems and run throughout the underground rootsystem (see page 5 for root description). Theseunderground rhizomes bear large, bulb-like, ridgedtubers. The root mass generally occupies the top15 cm of soil, though it has been found up to1 m below the surface in sandy soil. The root massin mature plants can account for 85% of the totalplant mass (Leah 2001).Flowering occurs from winter to mid-spring. Theovoid fruit is relatively large and begins green butripens to pale, translucent or bluish-white. Fruitsare present from late winter through to midsummerand are most prevalent on low growing (


The two forms of bridal creeper(Asparagus asparagoides)Common bridal creeper is widely distributed acrosssouthern Australia. Another form has also beenrecorded in South Australia and south-west Victoria.Both forms originate from South Africa.In 2003, amateur botanist Kath Alcock ofNaracoorte, SA, described and illustrated theWestern Cape form of bridal creeper that wasfirst discovered in the south-east of SA (Coles andWilling 2006). Further investigations revealed thatthis was a Western Cape form of bridal creeper,a form that is highly aggressive and apparentlyresistant to the bridal creeper rust fungus (Pucciniamyrsiphyllii), a biological control agent that wasintroduced to help control the common form ofbridal creeper. Western Cape bridal creeper couldpotentially reinfest vegetation where commonbridal creeper has been suppressed by eitherthe rust fungus or other control measures. It issuspected that Western Cape bridal creeper is adifferent species to common bridal creeper, but thescientific name A. asparagoides is currently usedfor both. Both forms are described below.Western Cape bridal creeper (Asparagusasparagoides Western Cape form)Origin and distributionWhile little is known about the history of WesternCape bridal creeper it is suspected that it wasintroduced along with the common bridal creeperas an ornamental. The distribution of the WesternCape form in its native range of South Africa isrestricted to the areas of ‘winter rainfall’ (where


Biology and threatIncursions of Western Cape bridal creeperin south-west Victoria and south-eastSouth Australia are being contained, andlocal efforts are underway to eradicate asmaller infestation in the Adelaide Hills.Habitat in AustraliaWestern Cape bridal creeper appears to favourhigher rainfall regions and coastal areas. It isknown to invade native bush corridors, roadsides,nature reserves and pine plantations, andinfestations can be found growing among commonbridal creeper. New infestations occur under birdperching areas such as tall trees and fence lines.Large numbers of seeds can germinate beneath theclimbing plants.Environmental impactsWestern Cape bridal creeper grows rapidly duringautumn and winter and forms dense curtainsof foliage that smother other plants. Althoughinfestations are currently not extensive, it has thepotential to spread further into most areas wherecommon bridal creeper occurs throughout southernAustralia. It can invade undisturbed habitats andis a major threat to most low shrubs and groundplants in mallee, dry sclerophyll forest and heathvegetation. Western Cape bridal creeper has aprolonged survival period over summer aftercommon bridal creeper has died back, therebydemonstrating its vigorous nature compared to thecommon form.Biology and ecologyThe growth habit of Western Cape bridal creeperis similar to the common form, but more robust.Western Cape bridal creeper is a climbingperennial plant (with annual foliage) that formsmultiple twisting stems that climb to 3 m high onsupporting vegetation and grow up to 6 m long.Its system of roots, rhizomes and tubers form athick mat just below the soil surface. The tubersWestern Cape bridal creeper (left) growing among common bridalcreeper (note rust fungus on common bridal creeper leaves givingthem a yellowish appearance)are different to those of common bridal creeperand are a distinguishing characteristic. They arelarge (40–75 mm long) and thick, and usually endin a fine root. They are arranged in a tight rosettearound the short rhizomes that grow close to theground surface.The leaf-like flattened cladodes (leaves) are broadat the base and pointed at the tips. They are a darkblue-green, and leathery with a waxy feel and arethicker and larger than those of common bridalcreeper.When the common form is growing in idealconditions, seedlings and leaves can appearsimilar, so it is important to look undergroundat the tubers to confirm identification.Shauna Potter22


Tracey HardwickeTracey HardwickeThe underground tubers are the best defining characteristic ofWestern Cape bridal creeper; they grow to 7.5 cm long and form tightrosettes that grow close to the ground surfaceThe leaves of Western Cape bridal creeper are generally larger, thickerand darker than the common formShoots appear after the first rains in early autumn.Germination appears to occur in the second winterafter seed set, in contrast to common bridal creeperwhere seeds generally germinate in the first season.Western Cape bridal creeper flowers two to threeyears after germination. Initial growth is rapid withwhite flowers first appearing in winter and fruitfirst appearing in late September. Berries are redand globe-shaped with three distinct lobes. Withberry ripening, leaves yellow and fall, and stemsbegin to dry out and die back in late spring to earlysummer, but can survive throughout summer inareas with sufficient summer rainfall and shade.Plants produce thousands of black seeds (about3.5 mm wide) each year and while viability is notconfirmed up to 90% is suspected.Like common bridal creeper, its main dispersalvectors are birds. Silvereyes, currawongs, blackbirds, wattle birds and emus readily consume fruits.It also spreads vegetatively through rhizomes indumped garden waste onto roadsides and intoremnant bushland.Correct identification iscritical. Land managersshould be on the lookoutfor Western Cape bridalcreeper and report suspectedinfestations to local weedauthorities.Vigilance is required from all landmanagers to ensure that this form ofbridal creeper is not growing on theirproperty. Any findings must be reportedto your local noxious weed managementauthority. An eradication program iscurrently underway in the Adelaide andMount Lofty Ranges region of SA (seecase study on page 95).Seasonal patterns for Western Cape bridal creeperFloweringFruitingGerminationFoliage presentSummer Autumn Winter SpringDec Jan Feb Mar Apr May Jun Jul Aug Sep Oct NovGenerally presentPresent in suitableconditions23


occur alternately along the length of wiry greenstems.Annual shoots emerge in autumn from a perennialroot system that consists of extensively branchedrhizomes and numerous tubers. These rhizomesand tubers form thick root mats extending 10–20cm below ground. Tubers range in size from 25 to40 mm long and 8 to 20 mm wide. The perennialroot mats make up at least 87% of the plantbiomass and allow the weed to persist year round,withstand disturbance and outcompete nativespecies (Raymond 1996).Flowers are white and scented. They appear inlate winter to early spring. Green pea-sized berriesturn pink, then red or burgundy in late springto early summer, and blacken upon maturity.Berries contain between 1 and 9 seeds. With berryripening, leaves yellow and fall and stems begin todry out and die back in late spring or early summer.However, stems can survive year round in areaswith sufficient summer rainfall.Common bridal creeper leavesCommon bridal creeper root systema depth of up to 10 cm and dry seeds can remainviable for at least three years (CRC 2004a).Hillary CherryBiosecurity SASeeds germinate readily under a wide range ofenvironmental conditions (Willis et al. 2003).Vegetative reproduction commonly occurs fromsmall sections of below-ground rhizomes. Therehave been no reports of regeneration from tubersalone but, as the tubers are attached to a rhizomethat runs extensively underground, care must betaken to ensure rhizomes are completely removed,if manually removing this plant from the soil. Theplant is able to persist mainly by way of the ‘budbank’, with numerous shoot buds located along therhizomes. Over 1000 berries per square metre maybe produced. Viable seeds readily germinate fromBridal creeper is capable of invading undisturbedsites, primarily through fruit-feeding birds (bothintroduced and native) that eat berries andexcrete seeds a long distance away. Commonbird dispersers include silvereyes, blackbirds, redwattlebirds, singing honeyeaters, common starlings,little crows, ringneck parrots and emus. Rabbits andfoxes also eat fruit and disperse seeds, and berriesmay be carried by water along watercourses. Othermethods of spread include dumping of gardenrubbish and machines such as graders along roadverges moving soil contaminated by seed or rootmass.Seasonal patterns for common bridal creeperFloweringFruitingGerminationFoliage presentSummer Autumn Winter SpringDec Jan Feb Mar Apr May Jun Jul Aug Sep Oct NovGenerally presentPresent in suitableconditions25


Biology and threatNew and emerging asparagus weedsSpecies Asparagus falcatus (sicklethorn) Asparagus retrofractus (Ming asparagus fern)Other names Protasparagus falcatus (L.) Oberm. A. macowanii Baker (pom pom asparagus or zig-zag asparagus)Origin Eastern and southern Africa Southern AfricaHabit Robust climber up to 6 m;capable of attaining largecrown size (>300 mm diameter)Shrubby plant growing 1–2 mand occasionally 3 m tallCladodes(leaves) andstemsFlowersYear round foliage; sickle-shape,shiny, dark green, elongatedcladodes 30–60 mm long, 3–5mm wide; stems with thornsthat become woody with ageSmall white flower clusters onelongated stalksYear round foliage; needle-likecladodes 7–45 mm long andproduced in clusters of 20–30along the stems; older stems arelight grey and bear small spinesSmall, white or cream; denseclusters produced in largenumbers on short stalksFruits Red rounded berry Rounded berries, initially greenturning purple to pinkish-redor with bluish bloom to black asthey matureRoots Form swollen tubers Form fleshy, tuberous rootsSheldon NavieSheldon NavieSheldon NavieMatt SheehanGlen Sanders Matt SheehanSheldon NavieSheldon NavieSheldon NavieCurrentknowndistributionStatus andspreadHabitatRecorded in Sydney and Wyong region at Lake Cathie, Sancroxand Port Macquarie in NSW; growing in Littoral Rainforest, WetSclerophyll, Swamp Oak and Subtropical Rainforest ecologicalcommunity typesEmerging environmental weed in south-eastern QLD and NSWcoastal areas; spread by birds and other animals that eat its fruitPrefers moist, semi-shaded growing conditions; common in riparianareas near human habitation; can germinate in conditions from fullsun to rainforest with >80% canopy closureRecorded in the Moreton and Wide Bay districts in south-easternQLD, Coochiemudlo Island, Greenslopes and St Lucia in Brisbaneand on the margins of a dry rainforest near Gympie; also observedgrowing in bushland at Ashgrove, Rochedale, Riverhills and MountCoot-thaEmerging threat in south-eastern QLD in urban bushland and alongwaterways; often cultivated as a garden ornamental and spread bybirds and other animals that eat its fruitPotential weed of riparian vegetation, forest margins, openwoodlands, urban bushland, coastal environs, roadsides anddisturbed sites; most commonly found in the understorey of drierforests26


Species Asparagus officinalis (garden asparagus) Asparagus virgatusOther names (edible asparagus) Protoasparagus virgatus Baker (Oberm.)Origin Native to northern Africa, Europe, western Asia and Mongolia Native to eastern and southern Africa and the Arabian PeninsulaHabitCladodes(leaves) andstemsFlowersFruitsErect or scrambling multibranchedperennial herb to1.5 m highFoliage dies back annually;cladodes are fine andcylindrical, 5–30 mm long and0.5–1 mm wide with a few ineach axilGreenish-white and solitaryin axils; spring to summerfloweringGlobular berries to 10 mmdiameter, red when mature;contain 1–9 seedsErect herb, climber or shrub0.4–0.8 m high; can attainvery large and continuousinfestationsYear round foliage; cladodesand branches spirally arrangedwith 3–6 cladodes in each axil;each cladode 6–20 mm longand 0.5–1 mm wide, slightlytapering and hairlessGreenish-white and solitary inaxils; spring floweringEgg shaped berries, 4–6 mmdiameter, bright orange whenmature; contain 1 seedRoots Form dense mat of rhizomes that arise from crowns Fibrous forms an extensiverhizomatous root massRob Richardson Rob RichardsonRob Richardson Rob RichardsonPeter Michael Sheldon NavieSheldon NavieSheldon NavieSheldon NavieCurrentknowndistributionStatus andspreadHabitatOccasionally naturalised in southern and eastern Australia (i.e. insouth-eastern QLD, eastern NSW, ACT, VIC, TAS, south-eastern SAand south-western WA); problematic in riparian areasCommonly grown vegetable plant that escapes cultivation and is anemerging weed of disturbed sites, wetlands and watercourses; anenvironmental weed in VIC and a potential environmental weed inWA, NSW, ACT, TAS and SA; spread by birds and rhizomesOccurs in disturbed areas and on roadsides and riverbanks and otherwet areas; widely cultivatedNaturalised in some parts of coastal and sub-coastal districts ofsouth-eastern QLD and less common in the coastal districts of centralNSWRegarded as a minor environmental weed in eastern QLD and as asleeper weed or potential weed in other parts of Australia (e.g. innorth-eastern NSW); spread by birds and other animals that eat itsfruitMainly found in riparian areas and near forest margins, or indisturbed sites near human habitation; can germinate in conditionsfrom full sun to rainforest with >80% canopy closure27

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