Alien species invasion is recognised as one of the most severe and challenging global environmental threats. Introduced species may become invasive and displace native species, modify habitats, change community structure, affect ecosystem processes or wider ecosystem functioning, impede the provision of ecosystem services, and cause substantial economic losses. Tree of Heaven, Ailanthus altissima (Mill.) Swingle, native to Southeast Asia is today considered one of the most widespread invasive plant species in Europe and North America and is a subject of modern invasion ecology research. A. altissima happens to be the research subject of the first PhD thesis in plant biology made by women in Croatia in the beginning of the 20th century, when the tree was cultivated as an ornament. Vjera Petaj, a passionate botanist and one of the first female students at the Royal University of Francis Joseph I in Zagreb (Croatia), used microscopy techniques for the investigation of morphology, anatomy, microchemistry, and biology of its extrafloral nectaries. All her results were later confirmed by modern microscopy techniques and contributed to the knowledge of their morphology and role in species physiology.
In this presentation an insight into social elements, particularly the status of women in the Croatian and European academic community in the early 20th century will be given. The results of this early microscopy work will be presented and linked with current research on the topic. The presentation will also focus on the ecology of A. altissima and its negative impact on the environment and human health. Conversely, potential ecosystem services, that this invasive plant species can provide, will also be discussed.