A review of the genus Lythrum (Lythraceae) in Western Australia, including typification of L. paradoxum

10 Pages·2000·2.5 MB·

by  B J Lepschi

Nuytsia 13(2):273-282(2000) 273
A reviewofthe genusLythrum (Lythraceae) in WesternAustralia,
includingtypificationofL.paradoxum
B.J.Lepschi
Western Australian Herbarium, Department of Conservation and Land Management,
Locked Bag 104, Bentley Delivery Centre, Western Australia 6983.
Present address; Australian National Herbarium, Centre for Plant Biodiversity Research,
GPO Box 1600, Canberra, ACT 2601, Australia.
Abstract
B.J. Lepschi. A review of the genus Lythrum (Lythraceae) in Western Australia, including
typificationofL.paradoxum. Nuytsia 13(2):273-282(2000). ThespeciesofLythrum(Lythraceae)
occurringinWesternAustraliaarereviewed,andtwonativeandonenaturalizedtaxonarerecognized.
Bothofthenativespecies,L.paradoxumKoehneandL.wilsoniiHewson,arenewrecordsfortheState.
Lythrum hyssopifoliaL., regardedas nativein eastern Australia, is treatedas introducedin Western
Australia. Afurtherspecies,theexoticL.junceumBanks&Sol.,isknownfromonlyoneoldrecord
andisnolongerconsideredtobenaturalizedinWesternAustralia. Akeyisprovidedforalltaxa,and
thedistributionofthethreeextantspeciesismapped. Aneotypeis also selectedforL.paradoxum.
Introduction
Lythrum L. (Lythraceae) is a cosmopolitan genus of approximately 35 species, represented in
Australiaby four indigenous and one introduced species (Hewson 1990). The genus has not been
comprehensivelytreatedsinceKoehne(1903),buttheNorthernTerritory species werereviewedby
Mitchell(1976)andallAustralianspeciesweretreatedinthe“FloraofAustralia”byHewsonloc. cit.
TwospeciesofLythrumarerecordedforWesternAustralia:L.hyssopifoliaandL.junceum(Hewson
1990). However, recent field and herbarium work by the author and colleagues has revealed the
occurrenceoftwoadditionalspeciesinthestate,L.paradoxumandL. wilsonii, andhasalsobrought
tolightadditionalinformationonthemorphologyanddistributionofthesespeciesandL.hyssopifolia.
ThisinformationispresentedaspartofareviewofLythruminWesternAustralia.
Materialsandmethods
ThisstudyisbasedonexaminationofherbariumcollectionsfromAD,CANB,DNAandPERTH,
with selected materialfrom BRI andNSW. All measurements weremadefromherbarium material
274 Nuytsia Vol. 13, No. 2 (2000)
(reconstituted where necessary). Conservation codes used are those adopted by the Departmentof
ConservationandLandManagement(seetheendofthisissuefordefinitionsofconservationcodes).
Introduced taxa are denoted with an asterisk.
Taxonomictreatment
1 Information presented here for previously described species is restricted to new data regarding
morphology,distributionandaffinities(andtypificationinthecaseofLythrumparadoxum). However,
afulldescriptionofL. wilsoniiisprovided,asrecentcollectionsofthisspeciesfromWesternAustralia
have expandedtherange ofmorphological variation previously known forthis taxon (e.g. Hewson
1990, Highet&Wilson 1991).
LythrumL.,Gen.PI. 1:446(1753).
SeeKoehne(1903) andHewson(1990)forgenericdescriptions.
KeytothespeciesofLythruminWesternAustralia
Inflorescenceasingleflower(veryrarelysome2-floweredinflorescences
mayoccur)
2 Hypanthium with pigmented spots atbase, petals4-6 mm long.
Stamens 10-12, 5-6 included andtheremainderexserted.
Stoloniferous perennial 2.*L.junceum
mm
2: Hypanthium withoutpigmented spots atbase, petals 2-4 long.
Stamens4—6 and included, orrarely 8-12 (with 4-6 included and the
remainderbarelyexserted) 1. *L.hyssopifolia
1: Inflorescenceof(1)2-7flowers
3 Stamens 8-12,exserted. Plantsglabrous 3.L.paradoxum
3 Stamens 4-6, included to exserted. Plants frequently minutely scabrous 4.L.wilsonii
:
1. *Lythrumhyssopifolia L.,Sp. PI. 1:447(1753).
Illustrations. Jessop(1986: Figure461 B); Rye(1987:Figure 132A-D); Hewson(1990: Figure33
G-I); Jeanes(1996:Figure 185J-I).
Descriptions. Jessop(1986); Rye(1987); Hewson(1990); Jeanes(1996). Seealsoundernotesbelow.
Selectedspecimens examined. WESTERN AUSTRALIA: Oxbow Lake, Warriup, 17 Nov. 1982,
G.J. Keighery5777(PERTH);baseofYellowdineRock,c. 500mWNWofYellowdineRoadhouse,
1 Dec. 1997, B.J. Lepschi3854 (PERTH); 19.4kmENEofJerramungupWoNnWroad to Ravensthorpe,
27Oct. 1997,B.J.Lepschi&B.A.FWirer3732(CANB,PERTH);c.29km ofEsperanceonroad
toMunglinup,29Oct. 1997,B.J. Lepschi&B.A.Fuhrer3807(PERTH); 16.1 kmSofGrassPatchon
WNW
roadtoScaddan,30Oct. 1997,B.J. Lepschi&B.A. Fuhrer3808(AD,PERTH);c. 11.5km of
Shackleton, 9 Feb. 1997, B.J. Lepschi & T.R. Lally 3392 (AD, CANB, PERTH); c. 1 km NE of
HowatharraHillReserve, 21 miles [c.34km] NofGeraldton,22Oct. 1976,D. &N. McFarlands.n.
(PERTH 04362497); Belleview [Bellevue], 26 Nov. 1953, R.D. Royce 4500 (PERTH); Yanchep
B.J. Lepschi, A review ofthe genus Lythrum in WA 275
NationalPark, 21 Dec. 1965,E.M. Scrymgeour 193 (PERTH);NutRd,Walpole-NomalupNational
Park, 15Dec. 1991,J.R. Wheeler2966(PERTH).
SOUTH AUSTRALIA: Yundi, 20 Feb. 1977, R. Bates 2602 (AD); Myrtlebank, c. 4 km SE of
Adelaide, 11 Nov. 1970, T.J. Smith 1882(AD).
NEW ZEALAND: Ramsgate Terrace, Mairangi Bay, 11 Dec. 1973, E.B. Bangerter 5124 (AD;
AK
n.v.).
CZECHREPUBLIC: nearMikulov,28Aug. 1963,M. Deyl258 (AD;PRn.v.).
UNITED STATES OF AMERICA: Camel Highlands, opposite Yankee Point, 17 July 1963,
E.K.Balls 12070(AD).
Distribution. Recenttreatments(e.g.Rye1987,Hewson 1990)givearelativelyrestricteddistribution
of L. hyssopifolia in Western Australia, bounded approximately by Yanchep, Albany and York.
However, L. hyssopifoliaisconsiderablymorewidespread inthisstate,extendingasfarnorth asthe
Howatharraarea(c.20kmNofGeraldton),easttoatleastYellowdine,andasfarasEsperanceandGrass
Patchinsouthcoastalandnear-coastaldistricts(Figure 1). Thecollections,however,areconcentrated
inthesouth-westcomerofthestate(intheareaoutlinedabove), withonlypatchyrecordsoutsideof
thisarea. Thisisalmostcertainlyduetounder-collecting,andfurtherfieldworkintheeasternwheatbelt
and western goldfields regions during late spring and summershouldreveal additionalpopulations
ofthis species.
LythrumhyssopifoliaalsooccursinNewSouthWales,Queensland,SouthAustralia,Tasmaniaand
Victoria,whereitisapparentlynative. PopulationsinWesternAustralianaretreatedasintroductions
(Rye 1987,Hewson 1990). Thespeciesisalsowidespreadthroughoutmuchoftherestoftheworld,
includingsouthernEuropewhereitisregardedasindigenous(Holmetal. 1979,Jessop1986,Hewson
1990).
Habitat. Lythrumhyssopifoliahasbeenrecordedgrowingindamptoinundatedsoils(rangingfrom
sands toclays), in avarietyofhabitats andvegetationtypes, ranging frommoreorlessundisturbed
areassuchasnaturalwetlandsandwatercourses,throughtohighlydisturbedsites(e.g.artificialdrains,
roadsides, suburbangardens, etc.). Itisalso anoccasional weedofirrigatedsummercrops (Hussey
etal. 1997),butisofnegligibleeconomicimportanceinthisregard. Lythrumhyssopifoliaoccupies
similar habitats in eastern Australia, where it is also recorded as an infrequent crop weed
(e.g. Cunninghametal. 1981).
Phenology. Flowering andfruitingrecordedbetween OctoberandFebruary.
Notes. DescriptionsofL. hyssopifoliaintheAustralianliterature(seeabove)recordtheinflorescence
ofthisspeciesasconsistingofasolitaryflowerborneintheleafaxils. However,asnotedbyKoehne
(1903),theinflorescenceinL.hyssopifoliamayveryrarelyconsistoftwoflowers. Thisconditionhas
been observed in Australian (e.g. Bates 2602, Keighery 5777, Wheeler 2966), as well as extra-
Australian material (e.g. Balls 12070, Bangerter5124, Deyl 258). The frequency oftwo-flowered
inflorescencesonindividualplantsofL. hyssopifoliaisalsoverylow,usuallywithonlyasinglesuch
inflorescence per individual.
LythrumhyssopifoliahasbeenconfusedwithL.paradoxumandL. wilsonii,butallthreetaxaare
amplydistinct. LythrumparadoxumdiffersfromL.hyssopifoliainflowerandstamennumberaswell
asstamenexsertion(althoughtheremaybesomeoverlapinthefirsttwocharacters),whileL. wilsonii
differsfromL.hyssopifoliainanumberofvegetativeandfloralfeatures; seeunderthattaxonforfurther
discussion.
276 Nuytsia Vol. 13, No. 2 (2000)
2. *Lythrumjunceum Banks&Sol.,inA. Russell,Nat.Hist. Aleppo,2ndedn,2: 253 (1794).
Illustrations. Jessop(1986:Figure461C); Hewson(1990:Figure33D-F); Jeanes(1996:Figure 185
G-H).
Descriptions. ReferencesasforL. hyssopifolia. Seealsoundernotesbelow.
Selectedspecimens examined. WESTERN AUSTRALIA: East Perth, Oct. 1902, C. Andrews s.n.
(PERTH).
SOUTHAUSTRALIA: Tantanoola,Nov. 1991,R. Bates26328(AD);nearMcLarenVale,c.25km
SSWofAdelaide,4Mar. 1956,R.N. Orams.n. (AD96413093;E,MEL,NSWn.v.).
NW
VICTORIA: 10.5miles[c. 17km] ofPeterborough,21Jan.1969,J.Anderson341 (AD;MELn.v.);
CondahSwamparea,Macarthur-Myaminroad,11Feb. 1969,A.C.Beauglehole&A.E.Orchard30520
(AD;MELn.v.)',BridgewaterLakes,21Jan. 1993,J.M. Dalby93/06(AD;MELn.v.).
Distribution. KnowninWesternAustraliafromasingleoldcollection. Thisspeciesdoesnotappear
tohavebecomeestablishedinWesternAustralia,andshouldbeexcludedfromtheflorarecordforthe
state. Naturalized in South Australia and Victoria, and also recorded fromNew South Wales and
Queensland on the basis of single, old specimens (Hewson 1990). Apparently indigenous to the
Mediterraneanregionandsouth-westernEurope,andwidespreadelsewhere(Holmetal. 1979,Hewson
1990).
Notes. AswithL. hyssopifolia,theinflorescenceinL.junceumhasbeendescribedintheAustralian
literature as a solitary flowerin the axil ofaleaf, buttwo-flowered inflorescences are occasionally
produced(Koehne 1903,Webb 1968). LikeL. hyssopifolia,suchinflorescenceswouldappeartobe
rare,buthave beenobservedin Australianmaterial (e.g. Bates26328).
LythrumjunceumcaneasilybedistinguishedfromallotherLythrumspeciesinWesternAustralia
byitsstoloniferoushabit,thepresenceofdark-pigmentedspotsatthebaseofthehypanthiumandlarge
petals.
3. Lythrumparadoxum Koehne,Bot.Jahrb.Syst.23Beibl.56: 19(1897). Typecitation:Australia
interior, in cl. Mitchell expeditione collecta (vidi in Herb. cl. Martius [= BR; see Stafleu & Cowan
1979]). Brisbane(numibicollecta?)comm.J.M.Bailey(vidiinmuseoreg.Berol.[=B]). Type: inspring
20 km SEofArkaroola, South Australia, 16 April 1990, R. Bates 22952 (neo: AD 99026150, here
nominated; isoneo: I n.v.).
Illustrations. Koehne(1903: Figure9C);Hewson(1990: Figure33 J-L).
Descriptions. Koehne(1897, 1903); Hewson(1990).
Specimens examined. WESTERN AUSTRALIA: Fanny’s Peak [Mt Fanny], c. 85 km S ofGiles
MeteorologicalStationonroadtoWarburtonMission,29Aug. 1973,B. Lay865 (AD, PERTH).
NORTHERN TERRITORY: RossRiverTouristResort,6Apr. 1983,P.K.Latz9839(CANB,DNA);
AmburlaStation, 18Oct. 1974,A.S. Mitchell'166(DNA).
SOUTHAUSTRALIA: McKinlayCreekEofNepabunna,GammonRangesNationalPark, 16Apr.
1990, R. Bates 22971 (AD, CANB; MY n.v.); creek near Balacanoona Homestead, 12 Dec. 1974,
L.D. Williams6405(AD).
B.J. Lepschi, A review ofthe genus Lythrum in WA 277
Distribution. InWesternAustraliaL.paradoxumhasbeenrecordedfromonesitesouthofGiles,close
totheNorthernTerritoryandSouthAustralianborders(Figure1). Lythrumparadoxumalsooccursin
thedrierpartsoftheNorthernTerritory,QueenslandandSouthAustralia(Hewson 1990). Thecentral
desert areas ofWesternAustraliahavebeen inadequately surveyedbotanically, and itis likely that
furtherpopulations ofL. paradoxum willbe found in suitablehabitatin this and neighbouring arid
regions(cf. L. wilsonii,below).
Hewson(1990)referredtoacollectionofthisspecies(WeldBlundell13),whichshesuggestedmay
haveoriginatedfromtheKimberleyregionofWesternAustralia. Thecollectionislabelled“Gordon
Downs”,andindeedthereisahomesteadofthesamenamesouth-eastofHallsCreekneartheNorthern
Territoryborder. However,accordingtoinformationreceivedfromtheQueenslandHerbarium(BRI),
theWeld Blundell collection originatesfrom anotherpastoral property, alsocalled GordonDowns,
approximately 50-70 km N ofEmerald in central Queensland (see also McLaughlin et al. 1979).
TwelveotherWeldBlundellcollectionsareheldatBRI,allfromtheQueenslandlocality, andthisis
undoubtedly where WeldBlundell 13 was collected.
Typification. Hewson(1990)commentedontheneedtotypifythenameL.paradoxum,butwasunable
toexamineanytypematerial. SearchesatBandBRdidnotrevealanytypematerialofL.paradoxum,
anditislikelythattheBailey syntypeseenbyKoehneatB wasdestroyedduringtheSecondWorld
War(B. Leuenbergerpers. comm.). Furthersearches atBM, BRI, CGE, E, K, M andW were also
unsuccessful. Intheabsenceofanytypematerial,aneotypehasbeendesignatedwhichpreservesboth
theoriginal and current(sensu Hewson 1990) circumscription ofthetaxon.
Habitat. ThesoleWesternAustraliancollectionofL.paradoxumisrecordedasgrowingina“rocky
gully”. IneasternAustraliaL.paradoxumoccursondamp,generallysandysoilsoncreeksandother
ephemeralorpermanentdrainageareas. Thereis noinformation availableon associatedvegetation
fortheWesternAustralian specimen, anddatais similarly sparseforeasternAustralian collections.
However,L.paradoxumhasgenerallybeenrecordedgrowingwithvariousgrasses,sedgesandherbs
characteristicofdampsites.
Phenology. The specimen from Western Australia, collected in August, is in flower and fruit.
ExaminationofmaterialofL.paradoxum fromeastern Australiaindicates the species mayproduce
flowersandfruitsinanymonthoftheyear,possiblyinresponsetorain. This islikelytobethecase
inWesternAustraliaaswell, butfurthercollectionsarerequired.
CALM
Conservation status. Conservation Codes for Western Australian Flora: Priority Three.
LythrumparadoxumispoorlycollectedinWesternAustralia,butisnotconsideredtobeunderthreat
given its widespread occurrence in adjacentparts ofeastern Australia. Additionally, the areafrom
whichL.paradoxumhasbeenrecordedinWesternAustraliaisremoteand under-collected,anditis
likely that additional populations ofthis taxon will be found with further survey activity.
Notes. LythrumparadoxumissometimesconfusedwithL.hyssopifolia,butthetwospeciesareeasily
distinguishable. See notes underL. hyssopifolia.
4. Lythrumwilsonii Hewson,FI.Australia 18: 322(1990).
Lythrumsp.Towrana(R.J. Cranfield2183).
Illustration. Hewson (1990: Figure33 M-O).
278 Nuytsia Vol. 13, No. 2 (2000)
Figure 1. DistributionofLythrumhyssopifoliaO, T.paradoxumA, andL. wilsonii 9 inWesternAustralia. Thesingle
early record of L. junceum is not mapped (see text).
B.J. Lepschi, A review ofthe genus Lythrum in WA 279
Ascendenttoerectannualorperennialherb,4.5-35cmtall,stemsangled,sometimeswoodyatbase.
Leavesalternate,frequentlyoppositeatthelowernodes(especiallyindepauperateplants), sessileto
mm
shortlypetiolate;petiole0-0.8 long;laminanarrowlyelliptictoellipticorrarelynarrowlyovate,
mm mm
2.7-24.5 long, 1-6.7 broad;baseattenuatetonarrowlycuneate;apexacutetorarelyobtuse;
margins, midvein (andveryrarelythelaminaalso) usuallyminutelyscabrous. Inflorescenceof1-7
flowers in bracteate cymes inserted in the upper leafaxils. Bract 1 (though sometimes absent in
1-floweredinflorescencesandfromthecentralfloweroffew-floweredinflorescences),verynarrowly
mm mm
ovatetosubulate,0.8-1 long,marginfrequentlyminutelyscabrous. Pedicels0.7-1.2 long,
mm
lengtheningto 1.7 longinfruit. Bracteoles2,insertedintheproximalc. 1/3ofthepedicel(though
sometimesabsent,especiallyfromthecentralfloweroffew-floweredinflorescences),lineartolinear-
mm
su.b5u-late, 0.4-0.7 long, margin frequently minutely scabrous. Hypanthium narrowly obconical
mm mm
to narrowly campanulate or (less often) more or less fusiform; 3-4.5 long, 0.6-1.2 wide,
longitudinally ribbed, frequently minutely scabrous. Accessorysepals4(-6), narrowly triangular,
mm
0.6-1.5 long, frequently minutely scabrous. Primary sepals 4(6), semitransversely elliptic to
mm
2tr.u5n-cate,shortlyapiculate,0.3-0.5 long. Petals4(6),obovatetoelliptic,pinktolilac, mauveor
mm
purple, 2-3.5 long. Stamens 4(6), included (not exceeding the primary sepals) or exserted
(exceeding the primary sepals and approximately level with the apices of the accessory sepals);
mm mm
filaments 0.6-3.2 long, anthers c. 0.3 long. Ovary cylindrical to more or less fusiform,
mm mm
1 1.8 long,style0.7-1.5 long,stigmacapitate. Capsulecylindricaltomoreorlessfusiform,
4mmlong. Seedsnumerous, angular-obovoid,lightbrowntoreddishbrown, c. 0.5 mmlong.
Selectedspecimensexamined. WESTERNAUSTRALIA: RowlesLagoon,7Nov. 1993,G.Barretts.n.
W(PERTH);2kmNEofTowranaHomestead,30Apr. 1982,R.J. Cranfield2183(PERTH);3.5kmdue
from North West Coastal Highway-Quobba Rd intersection, 24 Aug. 1995, G.J. Keighery &
N. Gibson2037(BRI,CANB, K,MEL,PERTH);ChagraWell,JimbaJimbaStation, 29Aug. 1995,
G.J.Keighery&N.Gibson2038(CANB,PERTH);unnamedclaypanonBoolathanaStation,onfence
c.0.5kmNNEofInnamanTank,24Aug. 1995,G.J. Keighery&N. Gibson2039(PERTH).
NORTHERNTERRITORY: LakeSurprise,32kmSWofTennantCreek,6May1994,P.K.Latz13705
(DNA);IlparpaSwamp,AliceSprings,22Feb. 1995,P.K.Latz 14034(DNA).
QUEENSLAND: GeorginaRiver, Sep. 1910,E.W. Bick 100(BRI);Braidwood,lundah,July 1960,
M.M. Coles.n. (BRI).
NEWSOUTHWALES: RooRooStation,Wentworth,8Sep. 1975,7.Eades.n.(NSW);WillowPoint
Station, 65 miles [c. 104km] NofWentworth, 18 Mar. 1959, L.A.S. Johnson & E.F. Constables.n.
(NSW).
SOUTHAUSTRALIA: WirrigilpinaSwamp,43kmWSWofStuartCreekHomestead,2Mar. 1984,
F.J.Badman655(AD);ClaytonRiver,c.95kmNofMarree, 15Nov. 1955,R.Hill'484(AD;GZU,MY
n.v.)\RoxbyDownsStation,c.60kmNofPimba,27Mar. 1973,B. Lay713 (AD;AKn.v.);Goyder
Lagoon,64miles [c.105km] SSWofBirdsville,24June 1966,D.R. Smyth65 (AD;SYDn.v).
Distribution. InWesternAustralia,L. wilsoniihasbeenrecordedfromtwowidelydisjunctareas:the
Camarvon-GascoyneJunctiondistrict, andRowlesLagoon,c. 70kmNWofKalgoorlie (Figure 1).
This disjunction is probably not a true representation ofthe distribution ofthis species in Western
Australia,andislikelytobetheresultofinadequatecollecting(cf.L. hyssopifoliaandL.paradoxum,
above). Lythrum wilsoniialsooccurs widelyinthearidandsemi-aridregionsofNew SouthWales,
theNorthernTerritory,QueenslandandSouthAustralia(Hewson 1990).
Habitat. CollectionsofL. wilsoniifromWesternAustralianhavebeenmadefromsimilarhabitatsto
those recorded throughout the rest of the species range in eastern Australia, namely damp soils
(predominantlyclays),onthemarginsofephemeralorpermanentwaterbodies. Vegetationcommunities
280 Nuytsia Vol. 13, No. 2 (2000)
recorded in Western Australia include herbland, samphire associations, shrubland and eucalypt
woodland. This is againsimilartowhathasbeenrecordedineastern Australia.
Phenology. FloweringandfruitinghasbeenrecordedduringAugust,NovemberandAprilinWestern
Australia. As with L. paradoxum (above), eastern Australian populations ofL. wilsoniihave been
recordedflowering andfruitingin allmonthsoftheyear,possibly inresponsetorain. Onceagain,
thismayalsoapplytopopulationsinWesternAustralia,butthereareinsufficientcollectionstoconfirm
this.
Conservationstatus. Whilecurrentlyknownfromonly afew sitesinWesternAustralia,L. wilsonii
isnotconsideredtobeunderthreat. ItoccurswidelyineasternAustralia,and,aswithL.paradoxum,
furthersurveysofsuitablehabitatinaridandsemi-aridareasofWesternAustraliaarelikelytoreveal
additional populations.
Notes. IndividualsofL. wilsoniifromtheCarnarvon area(e.g. Cranfield2183,Keighery & Gibson
2037-2039) differ slightly in stamen morphology from plants elsewhere in the species range. In
‘typical’ L. wilsonii, the stamensareincludedwithinthehypanthium(i.e. notexceedingtheprimary
mm
sepals),withthefilaments0.6-1.6 long,whileinplantsfromtheCarnarvonareathestamensare
exserted (i.e.exceedingthe primary sepals andapproximatelylevel withtheapicesoftheaccessory
mm
sepals),withthefilaments2.6-3.2 long. However,twocollectionsfromnorthernSouthAustralia
(.Badman 655, Lay 713) exhibit intermediate stamen morphology. In these plants the stamens are
mm
includedtobarelyexserted,andthefilamentsare2-2.1 long. PlantsfromtheCarnarvonareacould
potentiallybeaffordedseparatetaxonomicstatus,butthisisnotconsideredappropriateatthisstage,
given the existence of apparently intermediate individuals and the frequent plasticity of floral
morphologyintheLythraceae(Hewson&Beesley1990). Variationinstaminalmorphology(andalso
stamennumber)isalsoknowntooccurinL.hyssopifolia,inwhichtheremaybe4-6includedstamens
and occasionally 4-6 additional (barely) exserted stamens (Koehne 1903, Hewson 1990). Further
collectionsofL.wilsonii,particularlyfromWesternAustralia,wouldassistinclarifyingthisvariation.
Lythrum wilsonii is superficially similar to L. hyssopifolia, and the two species are sometimes
confused. Both taxahave a similaroverall morphology, but L. wilsonii can be distinguished most
readilybyitsinflorescence,whichconsistsof1-7flowers,asopposedtoL.hyssopifolia,inwhichthe
inflorescence usually consists ofa single flower (very rarely two flowers may be present in some
individuals). Single-floweredinflorescencesarenotinfrequentinL. wilsonii,especiallyinyoungor
depauperate plants, and some difficulty may be experienced in separating such individuals from
L. hyssopifolia. However,plantsofL. wilsoniigenerallybearatleasttwoorthreeinflorescencesof
twoormoreflowers,whereasinL.hyssopifoliatwo-floweredinflorescencesarecomparativelyrare,and
itisunusualtofindmorethanonesuchinflorescenceperindividual. Leafshapeand(tosomeextent)
stamennumberalso help to separateL. wilsonii andL. hyssopifolia, although thereis some overlap
inthesecharacters. LeavesinL.wilsoniiarenarrowlyelliptictoelliptic,rarelynarrowlyovate,whereas
inL. hyssopifolia leavestendtobenarrowly oblongin overall shape(though occasionally narrowly
ovate or rarely narrowly elliptic). Lythrum wilsonii has 4-6 (usually 4) stamens, while
L. hyssopifolia may have either4-6orrarely 8-12 stamens.
In her descriptions, Hewson (1990) records L. wilsonii as being “minutely scabrous”, and
L.hyssopifoliaas“glabrous”. ExaminationofherbariumcollectionsofL.hyssopifoliabythepresent
author have shown that the vegetative and floral parts of this taxon are also frequently minutely
scabrous,andasaresultthischaracterisnotexclusivelydiagnosticforL. wilsonii. Lythrumwilsonii
andL. hyssopifoliaalsoexhibitsomebroadecologicaldifferences,withL. wilsoniioccurringaround
.
B.J. Lepschi, A review ofthe genus Lythrum in WA 281
natural waterbodies in arid and semi-arid areas, and L. hyssopifolia occupying predominantly
disturbedhabitats,mostlyin themoremesicpartsofsouthernAustralia. Lythrumhyssopifolia does
occurwithintherangeofL. wilsonii,atleastinNewSouthWalesandSouthAustralia,buttherewould
appeartobe no documented instances ofactual sympatry.
Hewson (1990), whendescribingL. wilsonii, didnotspeculate on its relationships, apartfroma
comment that “...the two endemic species [i.e. L. paradoxum and L. wilsonii] belong in sect.
MesolythrumKoehne,anAustraliansection.” ThiswaspresumablybasedonthetreatmentofKoehne
(1903),inwhichL.wilsoniikeysouttosect. Mesolythrum(insubg.HyssopifoliaKoehne)onthebasis
offlowernumber,i.e.:(1)3-7flowersasopposedto 1(2)flowersfortheothersections. Asmentioned
above, L. wilsonii is morphologically similarto L. hyssopifolia, but it is notcertain whetherthis is
indicativeofany closerelationshipbetween thetwo taxa. Themain similarity betweenL. wilsonii
andL.paradoxumisflowernumber,whichisinherentlyvariableandmaynotgiveatrueindication
ofrelationships. Koehne’s (1903) classification is in need ofrevision, and the relationships ofthe
Australian species ofLythrum should be considered as partofa wider study aimed atpresenting a
modemmonographictreatmentofthe genus.
Acknowledgements
IamgratefultoNeilGibson,GregKeigheryandMikeLyonsfortheireffortsincollectingmaterial
ofL.wilsoniiintheCarnarvonarea,andtoDavidHalfordandRodHendersonforinformationregarding
the Weld Blundell collection of L. paradoxum. Thanks are also due to Alex Chapman, Beat
W
LeuenbergerandErnstVitekforsearchingfortypematerialonmybehalfatCGE,Band respectively
ThecuratorsofAD,BM,BR,BRI,DNA,E,K,MandNSWarethankedforallowingmetoexamine
collections intheircareorforfacilitating searchesfortypematerial.
References
Cunningham, G.M., Mulham, W.E., Milthorpe, P.L. & Leigh, J.H. (1981). “Plants ofWestern New South Wales.” (Soil
Conservation Service of New South Wales: Sydney.)
Hewson, H.J. (1990). Lythrum. In: George, A.S. (ed.) “Flora of Australia.” Vol. 18, pp. 100-104, 322. (Australian
Government Publishing Service: Canberra.)
Highet, J. & Wilson, P.G. (1991). Lythrum. In: Harden, G.J. (ed.) “Flora ofNew South Wales.” Vol. 2, pp. 198-200.
(University of New South Wales Press: Sydney).
Holm, L., Pancho, J.V., Herberger, J.P. &Plucknett, D.L. (1979). “A Geographical Atlas ofWorldWeeds.” (John Wiley
& Sons: New York.)
Hussey, P., Keighery, G.J., Cousens, R.D., Dodd, J. & Lloyd, S.G. (1997). “Western Weeds.” (Plant Protection Society
of Western Australia: Victoria Park.)
Jeanes,J.A. (1996). Lythraceae. In: Walsh, N.G. & Entwisle, T.J. (eds) “FloraofVictoria.” Vol. 3, pp. 909-911. (Inkata
Press: Melbourne.)
Jessop, J.P. (1986). Lythraceae. In: Jessop, J.P. & Toelken, H.R. (eds) “Flora ofSouth Australia.” Vol. 2, pp. 889-891.
(Government Printer: Adelaide.)
Koehne, E. (1897). Lythraceae. In: Urban, I. (ed.) Plantae novae americanae imprimis Glaziovianae. I. Botanische
Jahrbiicherfiir Systematik, Pflanzengeschicht und Pflanzengeographie, 23 Beiblatt 57: 18-36.
Koehne, E, (1903). Lythraceae. In: Engler, A. (ed.) “Das Pflanzenreich.”Vol. IV no. 216, pp. 1-326. (H.R. Englemann:
Weinheim).
McLaughlin, W., Lloyd, P.L. & Hodges, H.M. (1979). Peak Downs Shire Handbook. Unpublished report for the
Queensland Department of Primary Industries.
282 Nuytsia Vol. 13, No. 2 (2000)
Mitchell, A.S. (1976). A summary of the family Lythraceae in the Northern Territory (with additional comment on the
Australian material). Journal ofthe Adelaide Botanic Gardens 1: 55-59.
Rye, B.L. (1987). Lythraceae. In: Marchant, N.G. et al. “Flora of the Perth Region.” Vol. 1, pp. 366-367. (Western
Australian Department of Agriculture: Perth.)
Stafleu, F.A. & Cowan, R.S. (1981). Taxonomic Literature. Vol. 3, Regnum Vegetabile 105: 1-980.
Webb, D.A. (1968). Lythrum. In: Tutin, T.G. etal. (eds) “Flora Europaea.” Vol. 2, pp. 300-303. (Cambridge University
Press: Cambridge.)