The original version of Rose and Thorn, in this case just called the Thorn, makes her bow in Flash Comics 89 (nov. 47), in a story by Kanigher and Kubert.
With a wild costume, poisonous thorns and a tendency to spin around really fast, she was quite different from any of the villains the Flash had previously encountered.
Nearly half of the story was dedicated to her origin story, as two sisters are raised on a remote island. One is given a rose to study, and the other a thorn. But this origin story is a gigantic lie. The reader is cued in to the fact that the sweet Rose and the deadly Thorn are really the same woman, even though their physical appearance is different.
The Flash does not figure this out, and in fact thinks that the Thorn has perished at the end of the story, even though Rose is standing there crying.
The Thorn returns in a couple of months.