Del Tredici’s argument is that these spontaneous plants are “de facto native urban flora” considering the novel conditions produced by humans. It is an argument against perceiving spontaneous vegetation including invasive, non-native plants and plants considered as weeds, to be less worthy. Labelling a plant “invasive” or “weed”, says Del Tredici, gives people the licence to blame it for ruining the environment and to get rid of it.