Recently Discovered Stations of Carex bushii (Cyperaceae) in New England

Carex bushii Mack. (section Porocystis) is generally rare in the northeastern United States. It is currently ranked as S3 and special concern in Connecticut, SH from Maine, S1 and endangered in Massachusetts, S3 in New York, and S1 in Vermont. On 12 July 2018, I discovered a population of Carex bushii in a clayplain old field in West Haven, Rutland County, Vermont. Subsequent surveying of the property revealed 11 subpopulations of this plant, with a total estimated 58 genets with 685 ramets. As recently as Gilman’s 2015 New Flora of Vermont, this plant was considered state historic in Vermont, with no populations or voucher specimens known after 1964 (Gilman 2015). Since 2015, two populations were discovered in the Champlain Valley by the Vermont Department of Fish & Wildlife: one large population of approximately 50 genets and 265 ramets in Swanton, Franklin County; and a single genet in Cornwall, Addison County (R. Popp, pers. comm.). The West Haven population constitutes not only a new species record for Rutland County, but also now the largest known population of the species in the state of Vermont. Another interesting, recent expansion of its known range in New England was noted in 2012, when Lisa Standley discovered the first state record of Carex bushii in New Hampshire, growing on fill at an old air force base in Portsmouth (U.S.A. New Hampshire: Rockingham Co., Portsmouth, Pease International Tradesport. 7 June 2012, Standley s.n. [NEBC]). The nearest other known stations are a historic station in Sherborn, Middlesex County, and a current station in Ware, Hampshire County, Massachusetts, about 100 miles away (Natural Heritage and Endangered Species Program 2016). Carex bushii is morphologically similar to the more regionally common and sometimes co-occurring Carex hirsutella Mack., which may result in its misidentification when encountered in New England. The most reliable key diagnostic characteristic is the presence of