This is a report on chromosome numbers for 14 species of the subtribe Aveninae. which is largely naturalized in South Africa. This is the first chromosome number report for Helictotrichon longifolium (Nees) Schweick. (n = 14). H. longum (Stapf)Schweick. (n = 14). H. namaquensis Schweick. (n = 14) and Lophochloa cristata (L.) Hyl. (n = 7, 21/2. 14). The subtribe has a basic chromosome number of seven, and fewer ploidy levels occur in the naturalized species in South Africa than in the same species in other parts of the world. All tetraploid specimens were alloploids.

This is a report on chromosome numbers for the subtribes Phalaridinae and Alopecurinae (tribe Aveneae) which are. to a large extent, naturalized in South Africa. Chromosome numbers of 34 specimens, representing nine species and four genera, are presented. These numbers include the first report on Agrostis avenacea Gmel. (n = 4x = 28). New ploidv levels are reported for Phalaris aquatica L. (n = x = 7), Agrostis barbuligera Stapf var. barbuligera (n = 2x = 14 and n = 4x = 28) and A.  lachnantha Nees var.  lachnantha (n = 3x = 21).