Rupp was made deacon on 28 May 1899 and ordained priest on 2 June 1901. He began recording his botanical observations and specimens in 1892; from 1899 made 'a census of the native plants' of his parishes.
Rupp's ecclesiastical career began with his appointment as deacon on 28 May 1899 and his ordination as priest on 2 June 1901. He started recording his botanical observations and specimens in 1892; from then, he compiled a detailed account of the native plants in his assigned parishes.