Clara Blau was born in 1924 in
Cluj, Transylvania, Romania. Her father, Paul-Pinchas (1889–1948), was a journalist and a businessman and had a doctorate in international relations. Her mother, Sima (née Grünfeld, 1895–1990) was a housewife. Her brother is
Joshua Blau. In 1931, the family emigrated to
Baden, Austria, staying there until 1937, when they moved to
Vienna. 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. After one month in
Trieste the documents arrived, and they moved to
Tel Aviv. Clara studied at the teachers seminary and worked for seven years as an elementary school teacher. 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. 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. They had two children. During the War of Independence, she had to stop her studies and participated in the
Haganah activities and later served also in the
Israel Defence Forces. After the war, she competed her M.Sc. in botany (cytotaxonomy) in 1954 under the supervision of
Naomi Feinbrun. During her studies, Heyn also taught at the
Hebrew University Secondary School from 1950 to 1953. Heyn continued to study for a doctorate, which she completed in 1960. Her dissertation was on the “Monographic revision of annual species of Medicago L. in the sections Spirocarpos Ser. and Orbiculares Urb.” under the supervision of Naomi Feinburn and
Michael Zohary. She then published a book based on that dissertation. == Scientific career ==