Now, Heat has a reasonable idea of what a plant is. He's seen some nearby, and knew at least he shouldn't eat them or mess with the ones covered in spikes, but nothing at all in his fragmented knowledge suggested plants had gasses.

Why would he be searching plants for paint? Did plants have paint? Is that where it comes from in Nirvana? That sounded stupid, but a lot of things that happened in Nirvana might be stupid, and when he turns to address Vincent directly, he ... still seems offended by his presence alone. "What are you talking about? What gasses?"