With a brief overview of what is known to the author of the manuscript of the medieval botanical codex Liber de simplicibus BENEDICTI Rinij, kept at the Library of Saint-Marc in Venice, the opinion of the Italian sfoam Michelangelo Minio is accepted that the author of the codex can be the physician and doctor Nicolo Roccabonella, native to Conegliano. After working for more than thirty years in Venice on his manuscript, he spent four years, from 1449 to 1453, in Zadar, where he was able to acquaint himself with a certain Giovanni so-called Teotonico. According to the documents in the Zadar archives that Mirko Dražen Grmek consulted, as well as Giuseppe. Praga, there is evidence of the existence in Zadar of two pharmacists of Germanic nationality named Iohannes, one of whom had his pharmacy there since 1447. He can be thought of as the informant of Roccabonella for the few Germanic names, as well as for Croatian names (referred to by sclauonice). As an experienced trader and pharmacist, he had to learn and know the vernacular names of the plants he was trading in. These phytonyms are already present more than a century in Bogoslav Šulek’s botanical dictionary (Jugoslavenski imenik bilja, Zagreb 1879). They were copied on site by Š. And Šulek incorporated them into the dictionary as the oldest Croatian certificates. The graphics are very complicated and vary depending on the case. The handwritten codex contains phytonymic attestations in five languages: Greek, Arabic, Latin, Slavic (sclauonice) and germanic, for plants listed as tax-listed from 1 to 458. The Slavic component consists of 447 occurences of names listed for 368 plants (but not necessarily of different kinds). The contribution shows Croatian names which are known as names of contemporary Croatian phytonymy, e.g.: blitva, bor, HRAST, Jabuka, kapula, kupina, lan, poponak, Tikva, Vrba, žuka etc. Taking into account simple names and compound names there are approximately 100. Most of them are of Slavic origin, but they come from other idiomes, such as Dalmate, Venetian, etc. Furthermore, the phytonyms appearing in the Šulek dictionary as a unique certificate, but most of them are only variations of the shapes already attested, e.g.: bombak (beside bumbak), cafaran, soforan (next to coforan, cafran, čafran, safffran, šafran), garofal (next to garofan, garoful, garofuo), petrusimul (next to petrusin, petrušin, petrušimen, petrušimul), tkunja (next to Dunja, gdunja, tunja) etc. Among the Slavic botanical names of this codex, which appear in Šulek as unique certificates, we take into account a few who are now living in Czech: jutrocel, oeun, oeas, kvost and attention is drawn to a few certificates which can be read in a different way.