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Southern African Plants Naturalized in Australia: a Review of Weed Status

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Southern African Plants Naturalized in Australia: a Review of Weed Status 70 Plant Protecti on Quarterly VoI.7(2) 1992 distribution. In these cases it was usually Southern African plants naturalized in Australia: a not possible to decide whether the plants in Australia originated from southern Af­ review of weed status and biological control potential rica or elsewhere. The species were separated into those John K. Scott, CSIRO Division of Entomology, Private Bag P.O., Wembley with distributions centred in sub-Saharan Africa, but which include southern Africa W.A. 6014, Australia. (T), those species widely distributed in E.S. Delfosse, CSIRO Division of Entomology, GPO Box 1700, Canberra ACT southern Africa but which also occur in 2601 , Australia. Present address: National Bio logical Co ntrol Institute, USDA, sub-Saharan Africa (A); and those species APHIS, Office o f the Administrator, Federal Building, Room 538, which ex tend into Madagascar (M). 6505 Belcrest Roadd, Hyattsville, MD 20782 USA. Within the southern African region we have also indica ted those plants restricted (endemic) to so uthern Africa (S) and Summary those plants restricted (endemic) to the Forty-three families, 141 genera and 251 plants have become weeds of importance. Cape Floristi c Region (C). This area most spedes of southern African plants have The need for the bi ological control of closely resembles the Mediterranean cli­ been recorded as established in Aus­ weeds of southern Africa n origin has been matic region of southern Australia and is tralia, mostly in southern regions. The recognized for some time (Stride 1960), defined by Bond and Goldblatt (1984) as families with the most species are the but only recently have detailed surveys the south western Cape Province of South Iridaceae (20% of species), Asteraceae started. As part of the planning of re­ Africa, from the Olifants River Mouth to (15% of species) and Poaceae (13"Yo of sea rch on the biological control of weeds Port Elizabeth, incorporating most of the species). Sixty-eight species are re­ it is necessary to know which species fynbos (heath) vegetation type. Species garded as weeds and 33 species have come from southern Africa, and which distributions within Africa were taken been serious enough to warrant research species are a serious problem for the agri­ from Bond and Goldblatt (1984), and expenditure as measured by publica­ culture and environment of Australia. taxonomi c reviews listed in Gibbs RusseU tions. Significant weeds include Given the number of introduced weeds in ef al. (1985, 1987). Aretothull calendula, C/"ysaut/remoides Australia and limited research funds it is The presence of southern African spe­ moftili/ern, Cucumis spp., Emex also necessary to set priorities as to which cies in Australia was noted from state and australis, Eragrostis curou/n, Homerin weeds should be subject to a biological regional fl oras, Flora of Australia (1981- spp., Lycium /erocissimllm, Oxalis pes­ control program. 1990) and taxonomic revisions. The fol­ caprae, Peuuisetum mncrourllm, In this review we list southern African lowing were the principal references con­ Romillea rosea, Senecio madagas­ plants in Australia and assess their status sulted: Australian Capital Territory carieusis, Urocl,lon mnximum and as weeds. We then examine the priorities (Burbidge and Gray 1976); central Aus­ Zm'tedesc/Jin aetlriopicn. Most of these for the biological control of the more im­ tralia (Jessop 1981); New South Wales plants are agricultural problems. Sig­ portant species. (Ja co bs and Pickard 1981 ; Jacobs and nificant weeds of conservation areas are Lapinpuro 1986); Northern Territory inadequately documented at present, Methods (Hnatiuk 1990); Queensland (Hnatiuk but include De/airen odoratn, E1fr/Jnrta 1990); South Australia (Jessop 1984; Kloot erecta, Meliuis repens, Myrsip/Jyllum Cel/SIIS of sOlltherll Africal/ plants 1986); Tasmania (Buchanan ef al. 1989); nsparagoides, Polygnla spp., The selection of species was limited. by the Victoria (Forbes and Ross 1988); and Protasparagus a/ricaulls, Seuecio following definitions. A naturalized plant WestemAustralia (Green 1985, 1987). The pteropltonls and Watsouia spp. is a species alien to Australia that has Flora of Australia trea tment was accepted The southern African flora estab­ spread beyond the possibility of eradica­ in most cases where the distributions in lished in Australia was assessed for bio­ ti on and has existed as a reproducing the various references were not in agree­ logical control priority. Of the weeds not population for at least 25 years (see Kloot ment. Species names and authorities fol­ currently the subject of biological con­ 1986 for more on this aspect). We have low the usage in Gibbs Russell ef al. (1985, trol research, Oxnlis pes-capra#! was taken this definiti on in a wide sense and 1987) with a few exceptions based on identified as having the highest priority. have included plants that may be taxonomic treatments since 1985. Recent The assessment of the biological and adventive or casual (K loot 1986) if it ap­ synonyms in the Australian literature economic importance of Arctotlreca pears from the literature that they might were also noted because not all taxonomic calendula and weeds of conservation re­ be naturalized in at least part of their re­ changes are universa lly accepted and be­ serves were identified as research areas corded distribution. Species were also in­ cause of differences between the interpre­ requiring attention. cluded in the list where it was not possible tation of species names between southern to determine the degree of establishment. Africa and Australia. Common names are Introduction Southern Africa n plants were defined based on Hartley (1 979). An important part of the introduced nora as those species indigenous to the region in Australia is of southern Africa n origin. south of the Kunene and Limpopo Rivers Weed status The accidental transfer of plants to Aus­ (Botswana, Lesotho, Namibia, South Af­ Plants were recorded as weeds if they tralia has been favoured by climatic simi­ rica and Swaziland). The species found in have been described as such in the litera­ larities and southern Africa being on the this region are listed by Gibbs Russell et ture. The principal sources used were immigration route of European colonists. al. (1985, 1987). We have limited the spe­ Auld and Medd (1987), Hyde-Wyatt and In addition, the horticultural attributes of cies under consideration to those that Morris (1980), Kleinschmidt and Johnson a number of southern African plant fami­ have distributions restricted to sub-Saha­ (1977), Kl oot (1986), Parsons (1973) and lies, especially the Asteraceae and ran Africa. This was done to exclude the Tothill ef al. (1982). Species were given lridaceae, has ensured the deliberate in­ large number of species indigenous to important weed status only if they were troduction of a number of species which southern Africa, but which are cosmo­ the topic of research publica tions specifi­ have subsequently escaped cultivation politan or include Europe and/or Asia or ca ll y concerned with their detrimental at­ and become naturalized. So me of these elsewhere as part of their natural tributes in A ustralia. In this case checklists Plant Protection Quarterly VoI.7(2) 1992 71 and weed floras were excluded. An esti­ versible control should the agents be suc- Results mate of the level of importance of a weed. cessful. For this reason it was necessary to was obtained by counting the number of determine which southern African spe­ SOllthern African plants in Australia references to the weed in the abstracting cies were economica lly useful. We have attempted to list all southern Af­ journal, Weed Abstracts, from 1976 to Host-specificity and hence safety of in­ rican vascular plant species naturalized in 1990 (C.A.B. International). Only refer­ troduction isof primary importance when Australia, including 43 plant families, 141 ences to weed science, including biologi­ selecting biological control agents (mainly genera and 251 species (Appendix I). The ca l control, in Australia were counted. insects and fungi) . In practice, potential most important families are the Irida ceae biological control agents are often found (20% of species), Asteraceae (15% of spe­ Biological control potentwl to feed on or infest species closely related cies) and Poaceae (13% of species). Two The existence of potential biological con­ to the target. This implies that a search for thirds of the families (30) are represented trol agents can only be established follow­ biological control agents will be less likely by three or less species. Most species are ing thorough surveys in the weed's region to find suitably host-specific organisms found in Western Australia (143) fol­ of origin. Consequently no weed should on a weed in its natural range if it has lowed by South Australia (139), New be excluded as a potential target for bio­ many related crop and/or native species South Wales (135), Victoria (1l3), Queens­ logical control. However, priOrities can be in Australia . In contrast, weeds with no or land (66), Tasmania (51), Northern Terri­ establi shed based on the likelihood of few related species in Australia w ill have tory (14) and the Australian Capital Terri­ (inding host-specific agents, and the more potential biological control agents tory (14) (Appendix I). The distribution knowledge of insects and fungi in the re­ available since the level of host-specificity of most species is restricted to southern gion of origin that might be suitable for may be less critica l. The number of native Africa, whereas 37 extend into the rest of use as biological control agents. It is also species and genera in Australia was de­ Africa, including six also found in Mada­ important to know if there might be any termmed from the references used to es­ gascar, while 10 have their distributions conflicts of interest that would militate tablish the census. centred in sub-Saharan Africa .
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