The present study investigated the use of lexical bundles (LBs) in research articles authored by English L1 and Persian L1 academic writers, with a special focus on the syntactic roles of LBs in a larger context of sentence level. Four-word bundles were retrieved and classified structurally. The use of identified LBs was compared in two writer groups. The syntactic roles and relative complexity of the bundles’ structures were analyzed in relation to Biber, Gray, and Poonpon’s (2011) hypothesized stages of writing development. The results indicated different patterns of reliance on LBs, with Persian writers making greater use of LBs at higher frequency. In addition, Persian academic writers tended to use high frequency bundles differently from native-speaker academic writers. The results of the syntactic analysis of LBs reflected more frequent use of LBs functioning as compressing lexico-grammatical structures in a native English-speaker corpus, which is indicative of a more complex academic register compared to that of a Persian L1 corpus. The pedagogical implications of the findings for the explicit instruction of syntactically complex corpus-driven LBs for discipline-specific genre writing and suggestions for future research are discussed.
