Firstly, I would recommend searching the following on your browser: 'plant species identification gov'.
Also here are some resources that you might find helpful: you can search for a common list of invasive plant species in your country (such lists are available on Wikipedia, here is an example), alternatively you could use a local government webpage to search and identify invasive plant species in your specific region.
Dichotomous keys can be found on botanical/herbarium/environmental government websites, here is an example.
Lastly, apps like iNaturalist can identify plant species for you.