A “poop plant” is mentioned a couple of times in Semiosis:
The poop plant has proven possibilities for mischief. It looks like a pile of brown plump stems. — Chapter 3
The carved lid to a child’s chamber pot made me laugh out loud, but no one was in a mood to laugh, so no one looked pleased. “It’s the pattern,” I explained. It looked at first like the intricate pattern of lines on a Glassmaker tile mural. Subtle differences in the height of certain parts of the pattern revealed a small, low plant. “It’s a poop plant,” I said. — Chapter 5
Where did the idea for the poop plant come from? From Earth. Specifically, the Euphorbia decaryi from Madagascar. The succulent grows there in dry forests and shrubland, and like many other native species, it’s endangered due to loss of habitat and collection. For some ambitious gardeners, it makes an interesting and rewarding houseplant.
I used to live in Milwaukee, Wisconsin, and I first encountered the plant at the Mitchell Park Conservatory — also known as The Domes for its three domed greenhouses. The Desert Dome has a special Madagascar collection, including many kinds of Euphorbia. One day, during a visit, I saw what looked like a pile of old, dry turds on the ground. But no, it was the Euphorbia decaryi, with its lumpy grayish-brown stems bearing just a few leaves too tiny to notice. It didn’t look like something good to eat, which might serve as protection against predators.
The existence of a plant camouflaged as animal feces was a detail I knew I’d have to use in my writing — somehow. Eventually, I had the opportunity to have a little fun with it in Semiosis.
Our home planet, the Earth, is an amazing place. It has poop plants.