Alfirin was a flower of Lebennin. Legolas sang of it when he told of the Grey Company's passage through those lands. He described alfirin as golden and bell-shaped. Tolkien envisioned alfirin as:

"a beautiful bell-like flower, running through many colours, but soft and gentle ..." (Letters, #312)

In Unfinished Tales, a flower named alfirin is mentioned in the tale of "Cirion and Eorl," but there it appears to be a white flower reminiscent of Evermind or Simbelmyne.

Alfirin means "immortal."

Additional information provided by Mark Hoff.