Abstract
The dwarf palmetto (Sabal minor) is a widespread understory palm of the southeastern United States. This palm is expected to be one of the species that exhibits a range shift in response to climate change, and the population at the northwestern edge of its distribution in Oklahoma appears to be increasing in both numbers and extent. However, this palm may also be susceptible to cold damage during unusually severe winters, which could potentially limit the spread of this species. An unusually cold arctic outbreak spread across the southern Great Plains during 13–17 February 2021, with minimum temperatures of −11 °C recorded in Houston (Texas), −15 °C in San Antonio (Texas), and −26 °C in Oklahoma City (Oklahoma). In order to evaluate the effects of the arctic outbreak on Sabal minor, I examined individuals in four counties (one site in Brazoria County, TX; one site in Brazos County, TX; two sites in McCurtain County, Oklahoma; and two sites in Oklahoma County, Oklahoma) in the period of 5–16 March 2021. At nearly every site, 30 individuals were examined, and the number of palmate leaves as well as the extent of the green area on the leaf was visually estimated, with percentages rounded to the nearest 5%. There was little evidence of cold damage from southeastern Oklahoma to coastal Texas, with palmate leaves retaining a median of 85% green area. However, some damage was noted in seedlings at the northernmost population in McCurtain County, Oklahoma. In contrast, extensive leaf damage was noted in dwarf palmetto plantings in Oklahoma County, Oklahoma, with plants retaining a median of only 5% green leaf area. The results of this study suggest that arctic outbreaks are unlikely to prohibit the continued spread of this species at the northern edge of its native range but may cause damage to multiple plant growth stages that could reduce the rate at which the species survives and reproduces.