I've been listening to John Frusciante's 1994 album "Niandra LaDes and Usually Just a T-Shirt" which, by the way, is a truly great album. I've been wondering who the eponymous Niandra is/was. A quick search returned no clue of any person with that name, real or fictional. My guess was that it might be an anagram of some other name. I came up with Adrian Sladen/Ladsen/Lasden, among other things, but searches of those names failed to provide any meaningful hints. The only other mention of the name in the context of the album is an inscription somewhere on the cover that reads "For Toni Lovingly, Niandra LaDes" (Toni Oswald was Frusciante's girlfriend at the time). Any clue anybody?
Frusciante and his lover Toni Oswald were both interested in art, and were fans of the subversive surrealist Marcel Duchamp. They also enjoyed role reversals --dressing up in each other's clothes. The cover of the album is inspired by a self-portrait of Duchamp in drag, as a female alter-ego (anima) named Rrose Selavy. Similarly, John named his female alter-ego, calling her Niandra LaDes. (Other musicians have done similar things --Prince famously had an alter-ego named "Camille.")
I wasn't able to track down a definite source for why the name "Niandra LaDes" but there was an unconfirmed report on reddit that it's an anagram for a French dish. Duchamp was fond of puns, and "Rrose Selavy" is a play on a french phrase roughly meaning "Sex is life!" so it seems likely there's some hidden meaning here. The larger context, however, is an inside joke between John and Toni. The "just a t-shirt" line was also one of their inside jokes.