Dr. Alexander Eig is a figure of major importance in the history of botany in Israel. This paper attempts to evaluate, for the first time, personal contacts that influenced his academic development. Archival research reveals that his meeting with one of the greatest plant researchers of the 20th century, N.I. Vavilov, in 1926 had a great impact upon him. It was Vavilov who stimulated the young Alexander Eig to undertake his first taxonomic work and write his first monograph. This article reproduces and discusses a newly discovered letter, written by Vavilov to Yitzhak Volcani, the head of the Institute of Agriculture and Natural History in Israel, under whose leadership Eig began his academic work. This document points to the existence of a mutual understanding and cooperation between Vavilov and Volcani. Furthermore, Vavilov’s letter explains why Eig’s academic work, and that of generations of Israeli botanists who followed in his footsteps, chartered the path it took.