The manchineel tree looks fairly ordinary and pretty and makes fruits that look like apples, but it’s so toxic that if you stand underneath it in the rain, runoff will burn your skin. If it catches on fire the smoke can cause permanent eye and lung damage. The fruits taste sweet and alright at first with a “slight pepperiness” and then progresses to a sensation that has been compared to “your throat being torn apart,” followed by internal bleeding and a list of other possible symptoms that include the phrase “bacterial superinfection” as multiple toxic compounds ravage your entire system.
Deaths apparently ended with widespread hospital treatment but if you got lost in the woods and ate from one of these you’d be pretty screwed
The black spined iguana is apparently completely immune to all the manchineel’s various acids and poisons (because the same tree has several) and just hangs out in them while it kills everything else