Biological invasions have become a major concern in the past decades. It is generally accepted that an early detection of new alien species is essential because lag-phases (‘invasion debt’) are on average 20–30 years, meaning that today’s rare but fast spreading aliens may become tomorrow’s noxious weeds. In the past years it has become evident that an increasing number of non‐native vascular plants have become naturalized or even invasive without ever being noticed. A well suited approach for early detection of non-native species, even if these do not exhibit the diagnostic features required for determination, is DNA barcoding. This PhD project will focus on DNA barcoding of species from the genera Amaranthus and Chenopodium s.l. from the Amaranthaceae and Eragrostis and Panicum from the Poaceae to gain information about cryptic invasive species (‘invaders in disguise’) in Austria. For that purpose, the widely used plastid barcoding markers matK, rbcL, the newly suggested ycf1 and the nuclear ITS will be used. Additionally, invasion histories and dynamics will be inferred using species distribution modeling to forecast expansion of these weeds. It will be tested (i) if ‘invaders in disguise’ can be detected with standard DNA barcoding techniques, (ii) if DNA barcoding can help quantifying invasion debts of potentially invasive species in Austria; and (iii) if traditional alpha taxonomy in combination with DNA barcoding can improve accuracy of species identification and further refine taxonomic classification of cryptic invasive plant species. This project will be of relevance in developing management and monitoring strategies for invasive plants.