Danish botanist (1877-1946).
Henning Eiler (Ejler) Petersen (22 August 1877 – 22 May 1946) was a Danish mycologist, botanist and marine biologist. He made a major contribution to unveiling the mysterious die-back of eel grass in Northern European waters in the early 20th century as a pathogen outbreak. Petersen's main research was in what was then known as lower fungi – Chytridiomycota and Oomycetes, but he also studied the systematics of Red algae. Parallel to these lines of research, he investigated the intraspecific morphological variation in plant species – which would today be called quantitative genetics. The Oomyce