Now, I'm pretty sure everyone with an outdoor enclosure doesn't crawl around on their hands and knees looking for a stem off a single plant deemed poisonous for tortoises. I planned on taking chunks of 'sod' from our nearby park full of weeds and various flowers. I cannot ID everything there. On the chance that a poisonous plant ends up in the enclosure - does the tortoise know better? I mean, they HAVE to stumble upon some poisonous plants in the wild. Is there an instinct there? Or is that where natural selection comes in?