Clark sees the Tree, but it's burning, hot as the fire consuming him from the inside out. He can't even see what's going on around him anymore. There's nothing but the pain, and the fear, and wanting to just die. There's nothing left for him, he thinks, so there's no point.

Only the unbreakable thread, stretched thin by his poisoned mind, keeps him bound together with April. Keeps him holding on, even if he doesn't consciously realize it.