When Lady Gaga held a Q&A on Reddit for a 2014 album release, there was one question that took the botany world by storm: what’s it like to have a genus of ferns named after you? “Pretty cool,” she responded, “especially since it’s an asexual fern.” The 19 fern species of the Gaga genus are found from Bolivia to the south-west US, and were named after the singer partly for their G-A-G-A genetic sequence. “All sexless, judgeless,” she added. “How I wish to be.” The American singer and actor is among thousands of celebrities and figures, real and fictional, after...