Not really terribly impressed with this book. Its a real stretch to see how some of the 50 are considered by the author to be so important - pretty and useful they may be, but I don't think lavender and coriander are actually "world changing". Better candidates such as the tomato or maize are not included. Papyrus is rightly included, but the author makes no mention whatsoever of two crops without which there would be neither buildings nor books (and consequently no human civilisation whatsoever) - wood and paper. This is a huge ommission in terms of what the book is trying to achieve
Some of the authors' trains of thought are a little suspect - the pineapple (again, not a plant that I would consider as being a world changer) is directly credited with being responsible for the development of the commercial greenhouse. And the opening section of the pineapple chapter makes a huge and plonking generalisation along the lines of "Look at the suburbs of any northern European city and you will see miles and miles of greenhouses and polytunnels". I think not. Personally, I would have thought it was the orange tree, beloved by the French monarchs who developed the orangerie to protect it in winter, that really started the trend for the modern greenhouse.
Sometimes the tangent is enormous - when discussing pepper, the author briefly mentions the spice (indeed a world changing plant) and then blithely sidetracks to the sweet pepper or capsicum (to which the spice is not related botanically and which has nothing to do with the plant under discussion) and then devotes the rest of that section to it. This is bizarre, to say the least.
Some plants and their histories are given several pages, some only two. The overall style is cursory and somewhat sketchy. There is little attempt at any kind of narrative thread binding all these diverse plants together. The bibliography is extremely thin given the wealth of resources available and it appears that some sections in the book have merely been recycled from other sources.
Having said all this, the book is very accessible for the general reader - far, far more so than Henry Hobhouse's "Seeds of Change" which is probably one of its inspirations but not one which is listed in the bibliography. Those with a somewhat deeper understanding of the issues under discussion will best be served elsewhere, however.