He published mostly in German journals in Austria and is regarded as an Austrian botanist, as Galicia was at that time part of the Austro-Hungarian Empire.

In 1868 he traveled through southern Russia and a year later was appointed professor of Plant Anatomy at the University of Krakow.

Two parts of the listing appeared in a Polish journal in 1887–88, but because of friction the specimens were returned to Rehmann who sold them to Schinz in 1889.

To this day his specimens (partly organised and distributed in four exsiccata series[1]) may be found in herbaria around the world, including those of Krakow and Lemberg.

He described several new plant taxa, including a variety of the herb wormwood (Artemisia absinthium L. var calcigena Rehm.)