Plants stoloniferous and rhizomatous. Culms to 20 cm tall. Ligules of hairs; blades 1-1.5 mm wide, pubescent, at least adaxially. Synflorescences with 2-4 branches in a single whorl; axes 3-angled. Spikelets about 3 mm long. Glumes about 2 mm long, about 2/3 as long as the spikelets; lemma keels not winged; anthers indehiscent at maturity. 2n = 27.
Cynodon x magennsii is a natural triploid hybrid between Cynodon dactylon and Cynodon transvaalensis (Harlan et al. 1970). Several cultivars have been developed for lawns and golf courses in the the southern United States. These exhibit differing combinations of the characteristics of the two parent species.
Like triploid cultivars of Cynodon dactylon, Cynodon x magennsii does not produce viable pollen so its anthers remaing narrow and indehiscent at maturity. It also fails to set seed. Diploid and tetraploid plants of Cynodon dactylon also frequently fail to set seed because they are highly self-sterille, but they produce viable pollen and their anthers are well-filled and dehiscent at maturity.