How the lemon was invented (2018)
Citrus taxonomy is fascinating.  Of all the citrus that we have, there are only three "natural" plants: the mandarin, pomelo and citron.  Everything else is some cross between these:  https://en.wikipedia.org/wiki/Citrus_taxonomy, in particular, this graphic: https://en.wikipedia.org/wiki/Citrus_taxonomy#/media/File:Ci...