Born 1894, died 1969
A renowned botanist at the Catholic University of America. In 1944 he identified various plants depicted in the Voynich Manuscript as New-World species - though the Manuscript has been dated to the first part of the 15th century, a few decades earlier than Christopher Columbus' voyages. (The Viking discovery/exploration of North America/Vinland was some centuries prior to the manuscript's discovery, and of limited geographical range, so unlikely to have influenced the VM's creation, nor would the longer distance fishing voyages from northern parts of Europe.)
The article can be found on JSTOR here with a summary here.
Some further details here and [1].
Wikipedia's list of persons with the same name is at [2].