Beschreibung:
<jats:title>ABSTRACT</jats:title><jats:p>Trypanosomatids recently isolated from the plants <jats:italic>Euphorbia pinea, E. characias, E. hyssopifolia, Manihoi esculenta</jats:italic> (cassava) and <jats:italic>Lycopersicon</jats:italic> sp. (tomato) plus the McGhee‐Postell isolate of <jats:italic>Phytomonas davidi</jats:italic> have been examined for the presence of enzymes of ornithine‐arginine metabolism. Arginase (EC 3.5.3.1) was not detected in the flagellates examined whereas arginine deiminase (EC 3.5.3.6) and citrullinehydrolase (EC 3.5.1.20) were present in all organisms. <jats:italic>Phytomonas davidi</jats:italic> and the isolate from <jats:italic>E. hyssopifolia</jats:italic>, besides these enzymes, also had ornithine carbamoyltransferase (EC 2.1.3.3). The enzymic constitution of these flagellates is compared from a taxonomic standpoint to that of previously studied trypanosomatids.</jats:p>