In literature the van der Drift model of evolutionary selection has been successfully applied to explain the occurrence of < 0 0 1 > textured diamond layers which consist of closely interconnected, well-shaped crystallites as are regularly obtained by low deposition rate techniques like microwave and hot-filament CVD. In this study the growth conditions under which < 0 0 1 > fibre textured diamond layers can be obtained by flame deposition are investigated. For this purpose, the influence of different supersaturations and nitrogen concentrations on the texture, morphology and growth rate of the films is examined in detail. However, just as frequently reported in literature the textured surfaces obtained in these experiments are generally formed by differently sized, separately grown crystallites bounded by flat {0 0 1} top facets and rough, deteriorated {1 1 1} side facets. It is demonstrated that the occurrence of such a morphology is in contradiction with the model of evolutionary selection for which several prerequisites are difficult to fulfil in the case of diamond CVD. Therefore, an alternative so-called deterioration-gradient model is proposed by which the occurrence of < 0 0 1 > textured layers which consist of separately grown crystallites can be explained. (C) 2002 Elsevier Science B.V. All rights reserved.