On the bottom of bamboo roots there is a stamp that tells the season in which it was cut. We've been putting these season stamps on bamboo, and later pretty much every perishable food, for a long, long time.
These season stamps are marked on bamboo sets (せつ). You can't buy a single banana or a single grape, and just like that, if you want some nice seasonal bamboo, you have to buy them in sets.
Currently there are no similar looking kanji which exist in the WaniKani learning system