Season
Joint
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.
せつ
ふし
None
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.