Aim Reproductive traits are important mediators of establishment and spread of introduced species, both directly and through interactions with other life-history traits and extrinsic factors. We identify features of the reproductive biology of Australian acacias associated with invasiveness.Location Global.Methods We reviewed the pollination biology, seed biology and alternative modes of reproduction of Australian acacias using primary literature, online searches and unpublished data. We used comparative analyses incorporating an Acacia phylogeny to test for associations between invasiveness and eight reproductive traits in a group of introduced and invasive (23) and non-invasive (129) species. We also explore the distribution of groups of trait 'syndromes' between invasive and non-invasive species.Results Reproductive trait data were only available for 126 of 152 introduced species in our data set, representing 23/23 invasive and 103/129 non-invasive species. These data suggest that invasives reach reproductive maturity earlier (10/ 13 within 2 years vs. 7/26 for non-invasives) and are more commonly able to resprout (11/21 vs. 13/54), although only time to reproductive maturity was significant when phylogenetic relationships were controlled for. Our qualitative survey of the literature suggests that invasive species in general tend to have generalist pollination systems, prolific seed production, efficient seed dispersal and the accumulation of large and persistent seed banks that often have fire-, heat-or disturbance-triggered germination cues.Conclusions Invasive species respond quicker to disturbance than non-invasive taxa. Traits found to be significant in our study require more in-depth analysis involving data for a broader array of species given how little is known of the reproductive biology of so many taxa in this species-rich genus. Sets of reproductive traits characteristic of invasive species and a general ability to reproduce effectively in new locations are widespread in Australian acacias. Unless there is substantial evidence to the contrary, care should be taken with all introductions.

Aim Many Australian Acacia species have been planted around the world, some are highly valued, some are invasive, and some are both highly valued and invasive. We review global efforts to minimize the risk and limit the impact of invasions in this widely used plant group.Location Global.Methods Using information from literature sources, knowledge and experience of the authors, and the responses from a questionnaire sent to experts around the world, we reviewed: (1) a generalized life cycle of Australian acacias and how to control each life stage, (2) different management approaches and (3) what is required to help limit or prevent invasions.Results Relatively few Australian acacias have been introduced in large numbers, but all species with a long and extensive history of planting have become invasive somewhere. Australian acacias, as a group, have a high risk of becoming invasive and causing significant impacts as determined by existing assessment schemes. Moreover, in most situations, long-lived seed banks mean it is very difficult to control established infestations. Control has focused almost exclusively on widespread invaders, and eradication has rarely been attempted. Classical biological control is being used in South Africa with increasing success.Main conclusions A greater emphasis on pro-active rather than reactive management is required given the difficulties managing established invasions of Australian acacias. Adverse effects of proposed new introductions can be minimized by conducting detailed risk assessments in advance, planning for on-going monitoring and management, and ensuring resources are in place for long-term mitigation. Benign alternatives (e.g. sterile hybrids) could be developed to replace existing utilized taxa. Eradication should be set as a management goal more often to reduce the invasion debt. Introducing classical biological control agents that have a successful track-record in South Africa to other regions and identifying new agents (notably vegetative feeders) can help mitigate existing widespread invasions. Trans-boundary sharing of information will assist efforts to limit future invasions, in particular, management strategies need to be better evaluated, monitored, published and publicised so that global best-practice procedures can be developed.

Summary1. The possession of certain floral traits can determine which insects visit a plant species. If two species possess similar floral traits that determine shared flower visitors, floral traits can be said to mediate plant-plant interactions. Such indirect interactions are important for understanding fundamental relationships of plant communities, such as competition and facilitation but thus far have only been tested within a native community context. 2. We test whether floral-trait similarity can be used to predict interactions between an invasive plant and co-occurring native species in South Africa's Cape Floristic Region. We surveyed flower visitation at invaded and uninvaded plots across four sites and correlated floral-trait similarity between invasive and native species with both invasion impact on native flower visitation and flower visitor overlap of natives and the invasive species. 3. Similarity of all traits (categorical and continuous) and categorical traits alone explained invasion impact (flower visitor overlap) between the native and invasive species. The majority of flower visitor overlap was attributed to the native honeybee Apis mellifera subsp. capensis. 4. This study is the first to show that floral traits can be used to predict novel plant-plant interactions, even amongst ecologically generalized flower visitors and plants and to predict potential impacts of an invasive species on native flowering communities. However, floral traits were not useful for predicting changes in visitation to plant species. 5. Synthesis. Results advance our understanding of the role of plant traits in ecological communities and reveal that they are important in mediating not only plant-pollinator interactions but also plantplant interactions. Our findings also shed light on invasive-native plant interactions via pollinators and have the potential to predict certain invasion impacts.

a b s t r a c tFlowering invasive plants can potentially reduce pollination rates in co-flowering native plant species by attracting shared flower visitors. We investigate the effect of a prolifically flowering invasive species, Acacia saligna (Fabaceae), on native insect-flower interactions in surrounding communities. We surveyed flower visitation to A. saligna and selected native species at invaded and uninvaded areas and assessed the extent of flower visitor overlap of A. saligna and native species across four sites in South Africa's Cape Floristic Region. Median visitation rates of bees and all insects were significantly lower to one native species (Roepera fulva) in both field seasons at the same site when A. saligna was present. This native species also had the highest flower visitor overlap with A. saligna which was driven primarily by the native honeybee, Apis mellifera subsp. capensis. Observational data showed that A. saligna inflorescences were visited most frequently by minute beetles and the native honeybee. Our findings indicate that native honeybees are important visitors to A. saligna, and that at least one native plant species experiences reduced flower visitation due to competition with A. saligna for honeybee visits. Flowering A. saligna could have widereaching effects on native plants by competing for visits from a super generalist flower visitor -the native honeybee -which may jeopardize the reproductive success of natives whose flowering time overlaps with that of A. saligna. Our study further highlights the importance of understanding the effect of a flowering invasive species on native species and the potentially important mutualism between A. saligna and honeybees.

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