Re-annual plant

In addition to the more common annual plants, biennial plants and perennial plants, Terry Pratchett's fictional Discworld has a small number of re-annual plants. These are plants which, due to a rare 4-dimensional twist in their genetic structure, flower and grow before their seed germinates. This is usually only possible in areas with considerable amounts of background magic. Farmers who grow re-annual plants are usually very careful about dates of sowing, lest they cause devastating temporal paradoxes.

When re-annual plant products undergo fermentation, the product is time-reversed alcohol, a rare substance much sought by fortune-tellers and the like, as ingesting it allows some ability to foretell the future, which from the point of view of the plant is the past. Time-reversed alcohol produces inebriation in the normal way, but the hangover is thrust backwards in time to several hours before the actual ingestion of the alcohol. This is known as a hangunder, and is usually very strong since one feels so dreadful one imbibes large amounts to get over it.

The only revealed re-annual plant is the vul-nut, which is remarkable in that it can begin to flower as much as seven years before being sown.