Developmental and environmental effects on mineral nutrient concentration in birdsfoot trefoil (Lotus corniculatusL.) are not well documented. In this study, elemental composition of two birdsfoot trefoil stands were determined from a late vegetative stage through reproductive growth. ‘Norcen’ birdsfoot trefoil was established on a Glyndon silt loam (coarsesilty, frigid Aeric Calciaquolls) in Roseau County, Minnesota (49°N), in 1980, and Norcen and ‘Leo’ birdsfoot trefoil were seeded on a Waukegan silt loam (fine‐silty over sandy or sandy‐skeletal, mixed, mesic Typic Hapludolls) near Rosemount, Minnesota (45°N), in 1981. Shoot and root samples were taken at approximately biweekly intervals in the year following establishment. Shoots were separated into stems, leaves, umbels, and seed.