A particularly choice quote:
"From 1750 to 1850 Russia was making a fortune from trading rhubarb root through St Petersburg to Europe via the Baltic. Russia supplied and controlled the export of the dried root, thus controlling its price. It banned the export of the seeds to block the growing of the plant elsewhere. Catherine the Great took considerable interest in the cultivation and sale of rhubarb, as it helped to finance her military campaigns in Finland, Poland, Ukraine and Crimea. The price of rhubarb root rocketed! At one time the seeds were more valuable, weight for weight, than gold. To give some idea of the veneration that was given to the plant, Lord Stanhope, a Catholic peer, sent some rhubarb seeds to the Pope in a gold case, encouraging him to grow the plant in the gardens at the Vatican. This monopoly could not last indefinitely. Professor John Hope stated in 1770 that if 'Russian' rhubarb could be grown successfully in the UK, it would save the economy about £1 million a year (approximately £20–30 million in today's money)"