Lotus unifoliatus var. helleri (Carolina Birdsfoot Trefoil), is a candidate rare taxon of the Piedmont in North Carolina. The distribution of individuals in a Rowan County population was clumped. The abundance of individuals, their height, cover, and fruit production were negatively related with occurrences of Dichanthelium scoparium, Panicum anceps, and Liquidambar styraciflua. A field experiment indicated no significant effect of opening size in grassy vegetation on trefoil seed germination, survivorship, average height, and fruit production. A field clipping study suggested that roadside mowing prior to flower initiation may not reduce survivorship or fruit production to levels below those of unmowed plants.