Which is the most hayfever-prone city and is ‘botanical sexism’ to blame?

Allergy sufferers from Tokyo to London are struggling as pollen levels surge in cities, possibly due to a preference for male trees In 2016, Melbourne experienced a rare and extreme case of thunderstorm asthma that led to ten deaths and 8,500 people being abundant allergenic pollen. Some are dioecious plants, which have their own distinct sex, and some are monoecious plants (those with male and female flowers on the same plant) that have been cloned to be male. The last few times I was in London, for example, almost every single willow tree I saw was now a male clone; almost all of the bay trees being sold and planted were males; virtually all of the many species of poplar …