Soldiers Delight Natural Environment Area and Wildlands, a biodiversity hotspot in the Maryland piedmont, conserves an endangered serpentine oak savanna (“barren”) ecosystem with numerous rare, threatened, and endangered species. White-tailed deer became conspicuous during daylight hours circa 1994. In 2008, a helicopter-mounted forward-looking infrared camera (FLIR) survey estimated 36 deer/km2 (93 deer/mi2). A sharpshooter harvest was conducted in 2014, and public hunting was expanded beginning with the 2014–2015 season. This study investigated changes in percent cover, frequency, and importance percentage of herbaceous species using site data collected in 1993 and 1994 when deer were becoming conspicuous, in 2011 when deer density was extremely high, and in 2018 and 2019 after four to five years of expanded hunting effort. In addition, the level of impact to serpentine aster (Symphyotrichum depauperatum), an endangered serpentine endemic, was quantified using caged and uncaged plants. Gray goldenrod (Solidago nemoralis), common in 1993 and 1994, occurred in only one of the 37 plots in 2011 and none in 2018 and 2019. Serpentine aster had almost disappeared from all plots by 2011, but in 2019 was within 50% of 1993 mean percent cover levels. Number of flower heads and main stem length of serpentine aster were significantly different between caged and uncaged plants, except during the three years following the sharpshooter harvest. Data indicate that deer herbivory will continue to be excessive with only regulated public hunting. To prevent species extirpation, public hunting will need to be supplemented by additional deer reduction.