Y,jrqta1 (q. 3n -34'l (r9o) 3n List of vascular plants recorded from the Murchison Catchment Survey area 1985-1988 R.J. Cranfield Weslem Aultralian He6arium, Department of Conser|ation and I-and Managernent, P.O Bor 104. Ccmo. Wesrem Australia 6152 Abstract Cranfiel4 RJ. 0990). List of 823 valcular plsrts rccorded frorn tlle Murdison Carclrnent Survey area 1985-1983. Kingia I (4): W-347 (1990.). A coinprehe$ive list of lhe vasorlar dains ard a panial list of dle nqFvascular plarns of the Muctrison otdment area ar€ Pre'senred.An a.aohrof rc floristic cornpositicn of tle vegetation ofthis region is given. Bdefnoles on the ar€a's majorphysical feaDres and its climai€ arc also Fovided. Introduction This paperpresents a comprehensivelist of thevascular plants and a panial list ofthe non-vascular plantsof the Muchison carchmentarea resulting from the author's participation in an inventory and condition survey of the area carried out by officers of the Westem Australian Department of Agriculture and Depafinent ofland Administrationduring 1985-1988. The survey covered an arca of 85,000 km2 in which 2,000 sites were establishedand the vegetationofeach recorded. The areawas traversedextensively from April to Novembereach year resulting in 823collections and many observations. Due to thelimited accessand t1'pe of commercial activities carriedout in this region, along with the limited availability of water,there are several areas in nearpristine condition. This limited accesshas also restrictedcollections and altho[gh a species listinghas been produced it is in no waycomplete. The vegetationof the catchmentlands of the Murchison River (seeFigure l) presentsa broad spectrumof plantcommunities. The distributionsand characters of thesecommunities are mainly determinedby local factorssuch as landform, geology, soil type,hydrology, seasonal conditions, site history and rainfall reliability. Regionalfactors such as meanannual rainfall and long term climatic norms arefaidy uniform acrossthe region. Rainfall and moisture available in the north eastemportion of the region occurs,on long-term averages,as a combination of winterand summerseasonality (Nix 1982).The major part of theregion receivessufficientrain to promoteplant growth in thewinter months.More reliablev/inter rainsoccur on a gradienttowards the southwestresulting from incursionsof cold fronts from the mediterranean type climate of the South West Botanical Province. Becauseof the irregular occurrenceof both winter and summerrainfall thereare no clearclimatic boundariesreflected in the vegetation. There is howevera well-defined transitionalboundary separating the Eremaeanand SouthWest Botanical Provinces. Plant specieshave variously evolved to cope with a range in level and seasonalityof rainfall. The region thusfeatures a mixtureof sprecieswhich havewidespread distributions extending KingiaVol. I, No.4 Q90) southwardsfrom the Pilbam,and localised species which otherwiseoccur more widely to the southin thewetter south-wesl The distributionsof manyplant communitieswithin theregion are closely correlated wift the major 'Old geomorphologicalfeatues. High in lie landscaperemain fragmented areas of Plateau'surfaces dominated by sandplainsand edged by fericrete. These support a suite of speciest,?ical of sandplainsand dunes of CentralAustralia andof the SouthWest BotanicalProvince. Many areas have hard pan or be&ock close to the surface resulting in shallow soils. The underlying materials are extremely impervious to water and root penetralion,resulting in plans efficient in water retention,collection of moistureand drought stress avoidance. Meantemperatures within thearea vary ftom 18'-38"C in summerand 5'-20' C dudngwinter. This fluctualion influencesthe morphologicalcharacter of the flora andits phenology.The combinationof winter rain andcooler temperatures has allowed a prolific annualflora to flourish in tlle southwestem Murchison. The summerrains and higher temperaturesof the north are better suitedto annualand perennial grasses. Watercourses with alluvial deposits and extensive, principally saline lake systems, alter significandy speciesrichness and diversity. Such areassupport very different communities from thoseof the fairly well drainedcatchment lands. The lack of availablesurface water, except salt.lakes and deeppools along someof the rivers, hasan extremeinfluence on the vegetationin comparison with other facors. Soil types and micro-habitatsavailable within this area are fairly complex. Currendy there are approximately 80 recognisedland systemsand 14 basic soil types supporting some 27 major vegetation associationsplus a wide variety of vegetationassociations of limited occurrence(A.L. Paynepers. comm.). Hot dry prevailing winds in summerinfluence the vegetationstructure by reducingthe height of shrubs. In tiese shrublands,tall tlees (Ercalyptus spp.)arc absentexcept around watercourses and on the deepsandy soils of the Old Plat€ausurfaces. These shrublands are mostly composedof iough sclerophyllousplants of which .$tattles(Acacia spp.) dominate. Although watdes are extremely adaptable,in someareas they arereplaced by generasuch as Eremtphild spp.ot perennialgrasses. In mostinstances this replacement of watdesby othergenera reflects changes in soil t'?e. Shallow soilsas well aschemical characteristics, aspect and slope at any sitealso influence species composition. Otherwise,hisorical impactsassociated with grazingand overgrazing have caused major changesin shrubcomposition. The broad flat wash plains and leveesof the rivers becomewaterlogged for variableperiods in wet seasons.In many areashigh salinity or high minerallevels of the soil havecreated very specialisedhabitats. Numerousspecies of halophylesdominate saline areas. Suchassociations stabilizeotherwise erosion prone soils andaid in thecontrol of salt movementwithin the surrounding soils.The concentration of saltsin someof theseshallow basins over the summer is exfreme,placing sfiessfuldemands upon the halophyte communities. In areasaffected by highlevels ofmineralisation, other generaoccur; in somecases these may be indicatorsfor specific minerals. The presenceof a smallbut potentially significantnon -vascular flora (Table2) is worthy ofnote as many speciesof this groupact asnitrogen-fixing soil stabilisers.The crustingand surfacebinding of thelichens is especiallyimportant. RJ. Cnnfield, List of vascularplanls recorded fron rheMurchison Carchmenr Survey are3 1985- 1988 The complexnatue of the Murchisonvegetation is exemplifiedby the presenceof 37 known endemicor near endemicspecies, 4.570 of the total speciesin the surveyarea. Further, twelve rare and poorly collected specieswere discovered,l.SVo of the total collected during the survey. The rediscoveryof Eicrlerago tysoniana(,amiaceae) in 1985after ninety+hreeyears of obscurity is a primeexample. Many rangeextensions were noted and 23 weedspecies common in ihe SouthWestern Botanical Province were recordedin the southemportion of the survey area. An analysisof the growth forms of therecorded flora showthat annualsmake up 3lEo of thetot?ll speciescollected. A consistendyhigher annualspecies richness was observedin the south. This is likely to be due partly to tie lower temperatuesand more reliable moisture availability over the winter monthsand partly due to the more complex geomorphologyof the souliern areas. Remotenessfrom major cenEesofpopulation hasmade this an areaof greatbotanical intorest. It is also of considerablebotanical importance. Table 1 recordsthe 823 vascularplant speciesfound in ' 'Flora the Murchison catchmentArea. In comparisonthe areacovered by the of central Australia' ' (Jessopl98l) contains977 vascular plant species. Table 3 showsto whatextenttle Muchison flora is representatiyeof major plant families occuning in westem Australia. Especially notable is the Myoporaceaein which 6270of the western Australian taxa are found in the Murchison catchment Area. Table 1. Vascular Plant Sp€cies of th€ Murchlson Catchment Are_a Abulilott otocarpuln MRS274 P Ovalkaf Abulilon orycarpum MRS1009 P MRS1045 P RaspberryJarn MRS46? P RIC5344 P Mulga 2c5345 P Mulga Aca.ia bwk;ltii RJc5650 P FineLeafjarn Acacia ctridoviridis MRSTI P Aca.ia colletioidcs MRS364 Wair a Wlile Watrle Acacb afr. cmlgardbnsb MRS111 P Acacia craspedocarpa RIC5235 P Hop Mulga Acacia cuhbertsonii MRS52 P Acacb cypercphfla MRS5E P Minirirchie,Red Mulga Acacb dalriesioidzs RIc5260 P RIC5310 P Black Mulga MRS94 Snakewood(ps€udo) Acacia exocarpoides RIC5682 Acacia Srdsbyi P Miniitdie Acacia jitlxrdiageLrb RJc5259 P 2c5333 P Witcle{y Bush Acacb ligulata MRS17 P Umkella Bush Acatb ligulala x.t sonii RIC5406 P Acacia tinAhrlla RIC5432 P BowgadsBush Acacia longispirva RIC6076a P Acacia natrananba RIC5?r9 P Acacia nicrocaly RJC5375 P RJC609l P Fire Wattle Acacia n urophrlla MRS123 P MRS15 P Acacia pruinocarya P Gidsee(black) 330 KingiaVol. I, No. 4 (19m) Table 1 (continued). Yasorlar Plant Species of rhe Murchison Catchment Area MRS102 P Poofter Bush Aca.ia pt folia RIC5331 P Kr.rji Acacia quadrinarsiaza RICs09l P Acacia ^tr. quadrint/lrEinea MRS111 P E Mur.hisonWillow RIC5101 P Wanyr, Ho e Mulga Rlc5135 P Acacia odoplnoia Rrc5342 P Acocia atr. rhodophloia RIC5429 P MRS465 P Acacia nligaa MRS24T P GoldenWreath Wattle Acacia scleroclafu RIC6047 Acac;a sclercphyua MRS45O P Hard-Le3fWatd€ Acacia sclerospenv RIc5573 Silver BarkWatde MRS16 P MRS44 P Acacbterragonophy a P Curara MRS184 P P BardieBush Aca.ia atr. iphopflla MRS127 P Snakewood Acacia sp. @rUD MRSl024 P Acacia sp. (P48) MRSrm2 P AcacLl sp.