It’s not often a scientist reaches into fantasy literature for the perfect analogy. “Usually trees take a long time to respond to their environment,” said botanist Jennifer Blake-Mahmud. …A lot of trees have some type of flower, which contains their sexual organs. The showier plants, like cherry, magnolia and dogwood, flaunt their sexuality. …Only when the trees bloom can you figure out their sex. Lots of trees are hermaphroditic – that is, their flowers contain both male and female reproductive parts. …Acer pensylvanicum, a striped maple found in the northeast United States and southeastern Canada, is that rarest of species: Not only can it take a mere three weeks to bloom (a nanosecond in arboreal terms), but an individual tree can switch genders, from male to female.