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Experiments were conducted to evaluate root traits associated with nutrient exploitation following defoliation in three coexisting perennial grasses in a semi‐arid savanna. Root length density was determined within soil cores directly beneath plants, nitrogen uptake was evaluated by excised‐root assay with (¹⁵NH₄)₂SO₄, and mycorrhizal root colonization was estimated by observation of root segments. Root length density was lowest for Bouteloua curtipendula, intermediate for Eriochloa sericea, and highest for Aristida purpurea indicating that root length density was a more important trait for the mid‐seral than the late‐seral species. Rates of ¹⁵N uptake were greatest in the least grazing tolerant late‐seral species, E. sericea, intermediate in the mid‐seral species, A. purpurea, and lowest in the most grazing tolerant late‐seral species, B. curtipendula. Two successive defoliations reduced ¹⁵N uptake 60% in the late …