A small radish native to the Vale of Elfhame. It can be consumed by deer without any significant effects, but other species that eat the radish (whether raw or cooked) will suffer furious, noisy bouts of farting.
A skal pie (a/k/a "fart tart") is part of the plot of both "It's Only Funny Until Someone Loses Their Dignity" and "From Vulpitania With Love." In the first story, the end result of the use of skal pie results in skal being banned from the Empire outside Elfhame. In the second story, skal, and skal seeds, are part of the reason Westersloe Winterbough V is sent to Vulpitania, as the foxes there intend to incorporate skal into some of their joke and novelty products.