This is similar to a Kerry apple cake, but uses both apple and Japanese knotweed.
Knapple cake combines easy-going apples with more persnickety Japanese knotweed, an invasive, bamboo-like plant that can grow up to 15’ tall. The only edible part of knotweed is the young shoot, which, depending on where you live, is ready to harvest in April or May. They come up as bright red nubs first (and look a bit rude if your brain kinks that way), then turn into stalks vaguely resembling asparagus. Knotweed has a tart, refreshing flavour, and can be used like rhubarb in both sweet and savoury dishes.
Be wary of where you get your knotweed. It can grow just as well in polluted soil as clean soil. Check for historic commercial/industrial uses, use of pesticides, herbicides, chemical fertilizers, or other toxic materials. Learn more about knotweed and other wild urban edibles here.
1/3 cup butter
1/4 white sugar
1/4 cup brown sugar
Pinch of salt
1 cup flour (if using whole wheat, use only 3/4 cup)
1/2 tsp baking powder
1/2 tsp baking soda
1 tbsp vinegar
1/4 cup water
1 medium-sized apple, chopped
1/2 -3/4 cup peeled, chopped knotweed
Cream together butter, sugar and salt. Beat in egg. Add flour, baking soda and powder, vinegar and water. The batter will be stiff. Don’t worry. The water in the apples and knotweed will make the cake moist. Fold in the chopped apple and knotweed. The batter should look like you’ve got almost more fruit to batter. If it looks like there’s too little fruit, add a bit more. Press batter into greased 8×8 pan and bake in preheated oven 350 F 20-25 minutes or until top is golden brown.