futures traders didn't want a tulip, nobody accepted delivery of a tulip.
no tulips in the spot market were being traded anywhere near the futures month prices.
with that in mind, doesn't this make it one of the worst poster childs of irrational exuberance to cite?
Other sources give great detail of the tulip purchasing craze. For example, read the tulip chapter in 'Extraordinary Popular Delusions and The Madness of Crowds', by Charles Mackay. It cites many sources that detail the crazy high prices people did actually pay for tulips.
Between the contract categorization changes, actual shortages, and the bubonic plague, I think there are a lot of things that are unclear. Without the plague abruptly killing all the speculators would we have called it a bubble, or just an uptrend?