It might be very flowery in Death Valley (ironic or what?!) this year but here in my corner of north west England it gets less and less flowery every year. One of the big causes is eutrophication of soils. Motor vehicles not only emit CO2 in their exhaust gases but also oxides of nitrogen. These are not only bad for human health but they also end up in the soil and are potent plant nutrients. Paradoxically, this is bad for wild flowers. Eutrophied habitats become dominated by nitrogen lovers - like nettles and docks - and these crowd out more delicate species that can't compete. A motorway was driven through my area, a few decades ago, and as the number of vehicles on the road has risen relentlessly, year by year, plant diversity has continued to decrease.