After the Anschluss the family used their Romanian passports to leave Austria on June 8, 1938, and moved to Italy, while waiting to receive immigration certificates to emigrate to Mandatory Palestine.
In 1945 she started studying biology at the Hebrew University in Jerusalem, after being inspired by hearing a lecture on the topic from Yeshayahu Leibowitz.
[2] In 1946 she married Zalman Heyn, who was a poet and a songwriter, as well as the first spokesman and head of public relations at the Ministry of Labor.
In addition to Medicago, some of the genera she studied in depth were Trigonella, Lotus, Onobrychys, Lupinus, Prangos, Heptaptera and Calendula.
In 1962, she became part of the department of botany in the Hebrew University In Jerusalem and in 1978 finally received the rank of a full professor.
[3] Heyn was one of the founders of the Organisation for the Taxonomic Investigation of the Mediterranean Area (OPTIMA) in 1974, and served on its board and executive council until 1993.
Her last book Bryophyte Flora of Israel was published posthumously in 2004 (with Ilana Herrnstadt, Hélène Bischler and Suzanne Jovet-Ast).