The Killer Cashew

Sue and I are both biochemists, so we felt right at home talking with the scientists, and getting a perspective on some of their studies while visiting the biological research station in Santa Rosa National Park.

I also got an explanation for the blister that had persisted on my upper lip for over a week. We were talking with Eric Olsen, who studies insect populations by collecting their poop, when the subject of rainforest fruits came up. I mentioned that I had had a run in with a wild cashew, and showed him the blister. When we were riding from Naranjo to Santa Teresa I spotted a cashew fruit. I had seen pictures of the unusual structure; an egg sized smooth skinned orange lobe with what looks like a cashew nut sewn up in a dirty wrinkled leather pouch attached to one end. I wanted to break through the leathery covering to see the nut, but couldn't tear it with my fingers. Since I've never gotten past the age of two in some of the aspects of my oral development, my natural response was to put it in my mouth. As I tore through the skin with my teeth, I felt a searing pain on my lips and gums. Even a two year old would know to spit the damn thing out, so I did and washed out my mouth with the last of our lukewarm water.

Eric laughed and explained the strategy of the cashew fruit's physiology. As any monkey could tell you, I had bitten the wrong end. Even a two year old would have seen that the orange fleshy lobe looked more appetizing than the wrinkled leather pouch part, and that is exactly what the cashew fruit counts on for dispersal and survival. The fruit is built like it is so that animals will pick them and eat the tasty orange fruit, then hopefully discard the nut encased in its leathery pouch some distance from the original tree. The nut is the seed, and everyone knows that cashews are $10 a pound because they taste good and are good for you. It's not easy to discourage animals from eating the nut, thus the unappetizing leathery covering that is filled with nothing less than a cyanide solution. I was lucky to get away with a blister, but I'm still curious what it would have tasted like if I had bitten the right end.