Cheatgrass (Bromus tectorum) in a non-native grass that has invaded the natural range of the two wild potato species in the USA, so we sought to detect whether it suppresses Solanum jamesii (jam).  Preliminary tests showed that jam tubers often failed to sprout in cheatgrass sod.  We grew flats of 12 cheatgrass populations and dried and stored the straw and the media containing the roots.  In the following year, we again prepared flats of actively growing grass as well as flats with plain potting medium as control.  One tuber of each of 35 jam populations was planted in each of the 12 flats for each treatment:  Control, Grass, Straw, and Roots.  After about one month, no inhibition of shoot vigor was observed in any treatment compared to Control.  Percent shoots emerged in Root media was equal to Control at about 94%, but Grass (70%) and Straw (80%) were significantly lower.  The 12 cheatgrass populations inhibited jam tuber sprouting compared to control differently, as Grass (8% to 43% reduction) and as Straw (0% to 33% reduction).  Differences among jam populations were not significant.  Other factors like competition for limited water and nutrients could also make cheatgrass inhibit jam in the wild.  But even in these optimal greenhouse growing conditions, both live grass thatch and dead straw residue in the growing medium appear to be able to inhibit jam tuber sprouting.