The main objective of the article is to reveal the similar and different features of phytonym lexical units in the same language family, Oghuz group of Turkic languages: Azerbaijani, Turkic, Turkmen and Gagauz languages.Even though the same concept is expressed by similar or identical words in the languages belonging to the same language family, sometimes it can mean completely different meanings like homonyms.Also, with the adoption of Islam, the words of Arabic origin in the Azerbaijani, Turkish, and Turkmen languages formed a majority in the lexical layer of the language, compared to the language of the Gagauz Turks belonging to the Christian faith.Research method and methodology.In the article, the phytonym lexicon units included in the currently working vocabulary of the four languages of the Oghuz group: Azerbaijani, Turkish, Turkmen and Gagauz languages are studied in a comparative plan.Also, rich material related to four languages is compared using statistical, etymological, historicalcomparative, analysis and synthesis methods.Novelty of the article.Previously, units of phytonym lexicon in Turkic languages of the Oghuz group were not studied under a separate heading.This study can serve as a resource for those who study the similarities and differences between related languages at the lexical level, those who study the lexical layer of the Oghuz group of Turkic languages, and those who compile a dictionary related to the phytonym lexicon in Turkic languages in the future.Results.It is possible to see that there are a number of different points in the study of the phytonym lexicon in the Turkic languages of the Oghuz group.It is possible to see these either in the processing of words in different forms, in the feature of homonymy, as well as in the formation of phytonymic units in different forms.Differences in letter and sound changes are observed in words that are similar with minor differences.All this suggests that although the Azerbaijani, Turkic, Turkmen and Gagauz languages, which are part of the Oghuz group of Turkic languages, belong to the same language family, they have many differences in the lexicon of phytonyms.As the Azerbaijani, Turkish, Turkmen and Gagauz languages are included in the Oghuz language family, there are many similar words in their lexical fund.In the literary lexicon of Azerbaijani, Turkish, Turkmen, and Gagauz languages, similar words are sometimes written according to the same orthographic norm, and sometimes there are different spellings, even though the orthographic norm is expected.