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Acacia tortilis, A. karroo and Dichrostachys cinerea subsp. africana trees were divided into nine height classes, with increments of 0.5 m. The abundance of P. maximum growing under their canopies was estimated by scoring on a scale of 0 (no P. maximum) to 3 (P. maximum predominates). Presence of P. maximum was mainly associated with larger trees of all three species, and ranged from virtual absence under small trees to pure stands under larger trees. Spearman's rank correlations between tree height and the abundance of P. maximum (median score) were positive and significant. Panicum maximum attained pure stands (score 3) under smaller A. tortilis trees than under either A. karroo or D. cinerea. A median score of 3 was attained under A. tortilis, A. karroo and D. cinerea trees of >2.0 m, >4.0 m and >4.5 m, respectively. Tree height therefore represents a simple index of conditions favourable to P. maximum.