Аннотация
Crambe tаtariaSebe ́ok is one from four species of genusCrambe, which grow on theterritory of Kazakhstan. This species is listed in Red Data Book of Kazakhstan as rare endangeredspecies, and its natural habitats are chalk areas of west part of the country. The structure of sevenpopulations ofCrambe tаtariawas studied in the Aktobe Region. The optimum habitat conditionsfor this species are northern and northeast slopes of chalk uplands, chestnut and light-chestnutsoils. In unfavorable conditions of summits and southern slopes of lime uplands,C. tаtariacan forminvasive-regressive populations with the prevalence of virgin plants. The variation of the structureof the populations does not lead to a decrease in their resistance, which highlights high plasticity ofthe species within chalk uplands.