For convenience, the term Phytomona is used as the genus name for all trypanosomatids isolated from plants. This genus was created arbitrarily and was based on the host type: plant. However, they multiply in their insect vector which hosts morphologically identical trypanosomatids Leptomonas, Herpetomonas. The latter, and Crithidia-described as "monoxenic trypanosomes"-also grow in fruit. Finally, they can parasite different tissues: the latex vessels (there is no obvious pathological effect); the phloem vessels (sap), with pathological effect; in fruit, with some local symptoms, but the plant itself is not affected; indeterminate localization (on the surface?). The study of isoenzymes identifies distinct groups and confirms the arbitrary nature of the label Phytomonas. Several molecular markers identify the same groups, which correspond to the localization in tissues, their biological properties, and the geographic origin. The alignments of sequences of the ribosomal operon (18S, 5S, and ITS-1/ITS-2) differentiate the phloem trypanosomatids from all other isolates. The study of kinetoplastic DNA minicircles, the sequences of the SL RNA gene, characterize constant groups which identify at least different species, if not genera. Thus, there are two groups (species?) of pathogenic trypanosomatids which differ in terms of the size of their minicircle and the sequence of their genes SL RNA and 5S rRNA. The same markers can distinguish two latex isolates from the same region, and from the same host.