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Western wheatgrass is an important cool-season species in the Northern Great Plains mixed-grass prairie for ecological function, wildlife habitat, and livestock forage.� Western wheatgrass relies primarily on vegetative reproduction for recruitment. Daughter tillers are produced either from buds at the crown or buds along rhizomes. Crown daughters are relatively easy to study. Patterns of tiller recruitment from rhizomes are less understood because these are much more difficult to study without extensive excavation. They are, however, critical to understanding western wheatgrass persistence and responses to disturbances such as grazing and drought. We initiated a study to examine the impact of cattle and prairie dog grazing on rhizome tiller development on a ranch near Mahto, SD. In summer 2014, PVC collars (10cm diam. X 15 cm depth) were driven into the soil around western wheatgrass tillers ( ?1 tiller/collar) in exclosures preventing cattle grazing located both on- and off prairie dog towns. PVC collars restrict new rhizomes to the soil core within the collar, allowing relatively easy examination of rhizome and tiller development. Approximately 200 tillers were included on-town and 200 off-town; half of each were located on thin claypan and half on loamy ecological sites (ES). Half of on-town tillers on each ES were open to prairie dog grazing; the remaining tillers were protected. Half of off-town tillers in each ES received simulated cattle grazing in summer 2015; remaining tillers were ungrazed. PVC-collared soil cores were excavated in fall 2016. Crowns and rhizomes were carefully extracted from each core and plant components (crowns, rhizomes, and tillers) were mapped, rhizome lengths measured, and crown and rhizome tillers counted. Data were analyzed to evaluate the impact of grazer (prairie dog, cattle) and ES (thin claypan and loamy) on the vegetative reproductive strategies of western wheatgrass.