Which flower's speculative trade collapsed in the Dutch Republic in 1637?

The tulip. Bulbs of the rarest varieties reached prices comparable to a canal house, contracts were traded for bulbs still in the ground, and in February 1637 buyers stopped turning up at auction and the market simply stopped.

What made a bulb precious was a virus. The prized broken tulips, with flames of colour streaking the petals, were infected with a mosaic virus that disrupts pigment - and also weakens the plant, so the most valuable bulbs were the sickest and hardest to propagate. Nobody knew this until the twentieth century, and the varieties that commanded fortunes no longer exist.

The standard telling is largely nineteenth-century moralising. Anne Goldgar's archival work found few buyers who were ruined, no evidence of the suicides the popular accounts describe, and a trade confined to a small circle of merchants and craftsmen rather than a nation gone mad. The Dutch economy did not falter. What did happen was a serious crisis of trust and a wave of litigation - which is a duller story, and closer to what the records show.