The purpose of the study is to identify a complex of segetal plant species in the fields of agricultural crops. The surveyed area is located in the basin of the Osetr river and its tributaries the Osetrik and the Unitza in the Zaraysk municipal district in the south-east of Moscow region. The research was conducted in 2023–2025 using the route method on the discount areas of 100 m2. The frequency of occurrence of weed species was determined on a 5-point scale. There were studied agrophytocenoses of winter wheat (Triticum aestivum L.), winter triticale (×Triticosecale rimpaui Wittm. ex A. Camus), maize (Zea mays L.), soybean (Glycine max (L.) Merr.), field pea (Pisum sativum L.), and winter and spring rapeseed (Brassica napus L.). Ninety weed species of vascular plants belonging to 24 families have been identified. Among the families, Poaceae has the highest number of segetal species (19 species). There are 50 annual species, with Capsella bursa-pastoris, Chenopodium album, Matricaria perforata, and Consolida regalis being the most common. There are 40 perennial species, with Convolvulus arvensis, Cirsium arvense, Equisetum arvense, Taraxacum officinale, and Sonchus arvensis being the most prevalent in crops. Representatives of invasive flora have been noted at the edges of the fields, they are Conyza canadensis, Heracleum sosnowskyi, Epilobium adenocaulon and Amaranthus retroflexus. Arrhenatherum elatius has been identified as a potentially invasive taxon in soybean crops, while Veronica persica is often found in other agrocenoses. These facts should be taken into account when conducting field protection measures.