Watercress is one of the 80 plants in the book, a plant that has spread worldwide reputedly due to the habit of the Englishman for eating watercress sandwiches on the banks of rivers around the world (the stems root easily!). ;-) This picture of the Watercress line appeared in the on-line Guardian today:
The Watercress line was opened in 1865 and was well known for its early role transporting locally grown watercress to the markets in London. The section of the Watercress Line from Alresford to Alton is operated today as a Heritage railway and I remember taking the kids on it when they were small. I grew up not far away in Eastleigh.
Much more on this plant around the world in the book!