Hyacinth is originally a male name, in Greek; the flower name is taken from that. Does anyone reading this know enough French to know whether Hyacinth(e) is a flower-name in French as well as in English?
As a French-speaker, I can confirm this for you!
Hyacinthe is both a masculine and feminine name in French, though it is usually masculine. (It comes from the Greek name Hyacinthos.) The popular feminine variant in French is Jacinthe (pronounced Zha-saint). This comes from the popular Portugese Catholic apparition of Our Lady of Fatima, where the two girls who saw the apparition were called Jacinta and Lucia. Jacinta means "hyacinth" in Portugese, and Jacinthe was the French version of this popular saint's name. I must say that Hyacinthe is a very old-fashioned men's name. It would be like Winston in English.