A meaningless statement. Obviously we are dealing with relative diversity, not absolute. Western supermarkets in my experience (US, UK, continental Europe, Australia, New Zealand) are all very poor in diversity compared to markets in this particular area of China. Also, mushrooms are not classed as plants and this area has the largest diversity globally.
The power of the supermarkets seems to have been the main driver of this. Unless it's available globally in enough bulk to have permanent stock they just won't carry something any more.
Most of my favourite varieties of fruit and veg from less than 20 years ago are simply not available any more in supermarkets. I can remember regional variations and seasonality, even in Tesco. Now for apples it's Golden Tasteless, Braeburn and a few Gala and Cox if you're lucky.
We all lost something significant (taste) when they started caring more for supply chains than customers. Of course it's our own fault for preferring to get all groceries in one store.
Red "Delicious" if you're unlucky. Chosen for their shelf life, thick skin, and red color, and by the marketing spend of the organizations behind it. Chosen lastly (if at all) for their taste.
