Diectomis fastigiata (also known as Andropogon fastigiatus Sw.) belonged to the clade with other Andropogon, Schizachyrium, and Hyparrhenia species .
- , “Phylogenetics of Andropogoneae (Poaceae: Panicoideae) Based on Nuclear Ribosomal Internal Transcribed Spacer and Chloroplast trnL–F Sequences”, Aliso: A Journal of Systematic and Evolutionary Botany, vol. 23, pp. 530–544, 2007.
Diectomis fastigiata is a pantropical species.