The Sapu Tree is a carnivorous plant with "no upper limit" on the size of prey it consumes nor, presumably, on its own eventual size. It is native to the islands of Sumtri. It is an unfussy and indiscriminate eater, absorbing other plants, mammals as small as rats and mice, and creatures of increasingly prgressive size all the way up to Trolls. However, its digestive juices are not strong or corrosive enough to digest a troll, and trolls have been known to break out of the plant's all-enveloping flower with nothing more than the silicoid equivalent of econd-degree burns. It is believed that incautious research scientists who may well be the horticultural equivalent of Bergholt Stuttley Johnson have not only imported examples to the top-secret Cabbage Down research institute, they are cross-breeding it to the livelier variants of cabbage to be found in the Sto Plains. What they intend to do with it in a military context is unclear, and ecological action groups in Ankh-Morpork are known to be campaigning against this.