Abstract• We review current knowledge about the biology of the genus Acacia, and Acacia dealbata Link (silver wattle) in particular, as an invader in Europe, focusing on (i) the biology of the genus Acacia; (ii) biological attributes that are important for the invasiveness of the genus and A. dealbata; (iii) possible hypotheses for the invasion success; and (iv) control methods.• Several Australian wattles have been recorded as naturalized in Europe. Acacia has attained pest proportions in certain habitats and protected sites (notably coastal dunes, river courses, natural parks and biosphere reserves).• The spread of Acacia dealbata seems to be assisted by human interference such as soil disturbance and severe fires. The biological attributes favoring invasion by A. dealbata include tolerance of changing soil conditions, the ability to take advantage of environmental disturbance, phenotypic plasticity, vegetative reproduction, fire tolerance and allelopathic potential.• Different hypotheses explaining invasiveness and transition between invasion steps related to biological attributes as the key factor for A. dealbata invasion are discussed. Effects on the biodiversity of native flora are little understood and studies of suppression of autochthonous species are needed. It is desirable that further studies comparing Acacia at field sites in their native and exotic range should be done.• Understanding the biology of invasive wattles in Europe is the first step to an effective control method. Studies comparing plant invaders at field sites in their native and invaded areas seem to be most appropriate in order to be able to attack the most vulnerable stages. Mots-clés :Acacia dealbata / biodiversité / attributs biologiques / genre Acacia / espèces envahissantes Résumé -Le genre Acacia comme envahisseur : caractéristiques du cas Acacia dealbata Link en Europe.• Nous passons en revue les connaissances actuelles sur la biologie du genre Acacia et de Acacia dealbata Link, en particulier comme un envahisseur en Europe, en mettant l'accent sur : (i) la biologie du genre Acacia ; (ii) les attributs biologiques qui sont importants pour le caractère envahissant du genre et d'A. dealbata ; (iii) les hypothèses possibles pour la réussite de l'invasion et (iv) les mé-thodes de contrôle.• Plusieurs acacias australiens ont été enregistrés comme naturalisés en Europe. Acacia a atteint la proportion de nuisible dans certains habitats et sites protégés (notamment des dunes côtières, des cours d'eau, des parcs naturels et des réserves de la biosphère).• La propagation de l'Acacia dealbata semble avoir été aidée par l'intervention humaine, telle que la perturbation des sols et de graves incendies. Les attributs biologiques favorisant l'invasion par A. dealbata incluent la tolérance aux changements des conditions du sol, la capacité à tirer profit des perturbations de l'environnement, la plasticité phénotypique, la reproduction végétative, la tolérance au feu, et le potentiel allélopathique.• Différentes hypothèses expliquant le caractè...

This report synthesizes all aspects of the taxonomy, distribution, history of introduction and spread, ecological constrains (including preferred climate, substratum and habitats), responses to biotic and abiotic factors, biology (including phenology, vegetative and reproductive biology), economic importance and human uses, ecological impacts, legislation and management of Carpobrotus N.E.Br. (Aizoaceae), a prominent invasive plant in Europe.Carpobrotus species are mat-forming trailing succulent perennial herbs native from South Africa, introduced in Europe for ornamental and soil stabilization purposes since the beginning of the seventeenth century, now widely naturalized on coastal habitats of southern and western Europe. C. acinaciformis and C. edulis are the main species recognized outside South Africa, together with their hybrids and potential hybrid swarms. Identification conflicts both in the native and invaded areas raise doubts on the taxonomy of these taxa, but hybridization processes may boost adaptive changes in the invaded range.The release of Carpobrotus in natural environments and protected areas is prohibited in several European countries, but this taxon is not included in the list of invasive species of Union concern. Carpobrotus is a pioneer of disturbed sites and coastal areas including cliffs and sand dune systems, due to its tolerance to stress factors such as salinity, drought and excess of light. Carpobrotus invasion ultimately affects patterns of native species diversity. Moreover, it has been recognized as a major driver of soil conditions shifts and soil geochemical processes disruptions, representing a serious threat for coastal habitats.Management plans for Carpobrotus must consider its high plasticity for morphological and ecophysiological traits, which may probably explain its tolerance to a wide range of ecological conditions. Its flexible mating systems, which represent an optimal strategy to facilitate local adaptation and habitat colonization, include ability to produce apomictic seeds, selfand cross-pollination, and an intense vegetative clonality. In addition, Carpobrotus produces a large seed bank with a moderate short-term persistence, and fruits are effectively dispersed by mammals. The most efficient control methods are physical removal and herbicide application on leaves, whereas integration of biological control with other conventional management methods are likely to be most effective. A long-term monitoring of control actions and restoration of soil conditions are needed to prevent recovering from clonal parts, seed bank or mammal faeces as well as potential new invasions by other opportunistic species. Taxonomy Names and classificationScientific name: Carpobrotus edulis (L.) N. E.Br., 1926 Basyonym: Mesembryanthemum edule L., 1759

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The tree Acacia dealbata Link is an Australian woody legume that has become a serious environmental problem in Northwest Spain, where its expansion is assumed to reduce populations of native species and threaten local plant biodiversity. In order to investigate the potential involvement of allelopathic mechanisms in this process, net photosynthetic and respiration rates of four test native understory species (Hedera hibernica (G. Kirchn.) Bean, Dicranum sp., Dactylis glomerata L. and Leucobryum sp.) were evaluated using a Clark-type electrode in the presence of canopy leachate collected under A. dealbata stands at four times of the year for 2 years and macerate from their apical branches at the same sites and times. The first two test species were present both inside and outside of A. dealbata stands, while the last two were only located outside the stands. We found that there were significant differences in respiration and net photosynthetic rates between the control and A. dealbata extracts in all test species. The respiration rate was increased by both canopy leachate and macerate extracts on certain collection dates, but net photosynthetic rate was stimulated by macerate and inhibited by canopy leachate on other dates. The main phenological stages of A. dealbata in which respiration and net photosynthetic rates were more affected were blossoming, inflorescence formation and in periods after severe drought, in this decreasing order. Our results also showed that Dicranum sp., Leucobryum sp. and D. glomerata were more affected by aqueous extracts than other species during a 2-year period. We suggest that the observed inhibitory or stimulatory effects on the physiological parameters studied could have an adverse effect on the understory species, and that allelopathic interference seems to participate in this process.