I had a ranger demand to know if I was “stealing” plants because I parked at a roadside to photograph some. And the usual raised eyebrows and pointed questions from security guards and the likes. Not been bothered by any cops yet, but I go out of my way to avoid places where those are likely to be.
The best tactic I’ve found is to take a big breath and launch into an enthusiastic, and unnecessarily technical explanation of the organism in question, why it’s cool, how people need to understand its conservation status better, the failures of local government regarding its protection, and any other details I can think up - even the most inquisitive meddlers get glazed eyes and attempt to escape before long. It’s important to talk fast and not let them get a word in edgeways, but don’t be aggressive, just excessively informative. Bonus points if you can ask them to take action in some way, like writing to their congressman.