So are you going to fight the citation? Better have lots of pictures with botanical data on all the plants growing in your lawn. Seems the key element here is the legal definition of a prohibited weed. If you go to trial, give the officer some rope and see if he’ll hang himself. Ask if he’s an expert on identifying weeds. If not, how does he know your yard had weeds? Otherwise pursue his qualifications. What training is he relying on to identify weeds. Make him define a weed. If it’s substantially different from your legal definition, ask whether he’s aware of the legal definition. Introduce the legal definition and have him read it. Then ask if in light of his newly acquired knowledge, does he still maintain that your yard had weeds. If not, citation dismissed.