【Aim】 Bromus sterilis, B. rigidus, B. diandrus, and B. tectorum have been recognized as invasive weeds because they are harmful and their seeds (florets) make their way into China through imported agricultural products. The morphological characteristics of these species are very similar; hence, further studies on their identification methods are required. 【Method】 External structures such as spikelet axis, basal disc, palea, and lemma of four types of bromegrass florets were morphologically observed and compared using light microscope (LM) and scanning elactron microscope (SEM). 【Result】 The lemma veins of B. strilis are arranged in a ridged pattern; B. tectorum has long hairs located on the ridge of the palea and significantly collapsed rachilla scars; and the rachilla and callus scars of B. rigidus are significantly elongated. These macroscopic features can be used in identification. Micromorphology can be used to distinguish characteristics, including the distribution density of crown cells in the palea and lemma. 【Conclusion】 A combination of macroscopic and micromorphological features can be employed in the identification of four species of Bromus seeds.