[Facts] Re: Sharon and Vanessa
Sharon was inspired by The Song of Solomon 2:1 where it says @I am the rose of Sharon, and the lily of the valleys'. It transfered to use as a name in the 20th C. with other botanical names, in reference to the yellow-flowered shrub and a species of Hibiscus. In Steinbeck's novel The Grapes of Wrath (1936) one character is Rosasharn (Rose of Sharon). Those two sources, botanical and Biblical, have been responsible for the endurance of the name, though sympathy for Sharon Tate may have inspired some mothers in the years following her death.
Vanessa is also literary, created by Jonathan Swift for his friend Esther Van Homrigh. Someone, somewhere, pulled out of thin air that it must mean 'butterfly' and some editor didn't smack them. Thus the supposed and utterly false meaning helped buoy it in the nature-naming days of the late 60's and early 70's. Association with Vanessa Redgrave and more recently Vanessa Mae doesn't appear to have done it any favours as far as popularity goes.
Devon