"... it was one of the few places on the Disc where plants produced reannual varieties.
Reannuals are plants that grow backwards in time. You sow the seed this year and they grow last year.
Most's family specialized in distilling the wine from reannual grapes. These were very powerful and much sought after by fortune-tellers, since of course they enabled them to see the guture. The only snag was that you got the hangover the morning before, and had to drink a lot to get over it.
Reannual growers tended to be big, serious men, much given to introspection and close examination of the calendar. A farmer who neglects to sow ordinary seeds only loses the crop, whereas anyone who forgets to sow seeds of a crop that has already been harvested twelve months before risks disturbing the entire fabric of causality, not to mention acute embarrassment."