Canaan Valley (hereafter, the Valley), in northeastern West Virginia, supports large areas of wetland, upland forest, and upland non-forest habitats at relatively high elevations, providing potential habitat for a variety of rare plant species. The presence of 54 species of plants considered to be rare and of conservation concern in West Virginia plus 22 watchlist species has been confirmed in the Valley. No federally listed threatened or endangered plants have been found. One of the rare species is the globally critically imperiled Platanthera shriveri (Shriver's Frilly Orchid) and 4 are globally vulnerable—Gymnocarpium appalachianum (Appalachian Oak Fern), Hypericum mitchellianum (Blue Ridge St. Johnswort), Euphorbia purpurea (Glade Spurge), and Polemonium vanbruntiae (Bog Jacob's-ladder). Rare plants are found throughout the Valley; 80% occur in wetlands, and a significant assemblage is associated with wetlands on Greenbrier Limestone. Globally rare species are Appalachian endemics, but 41 of the Valley's rare and watchlist plants are primarily northern in distribution. Extant native populations are known in West Virginia only from the Valley for 3 species—Carex atherodes (Awned Sedge), Gentianopsis crinita (Greater Fringed Gentian), and Viburnum trilobum (American Cranberry-bush)—and a significant portion of all known West Virginia occurrences for at least another 16 species are in the Valley. Several rare plant species grow in multiple places in the Valley, but others are known from only 1 or 2 sites and are quite vulnerable. Non-native insect pests threaten Abies balsamea (Balsam Fir) and Fraxinus nigra (Black Ash). There are a number of threats to the Valley's rare plants: invasive plants, especially Typha latifolia (Broadleaf Cattail), Iris pseudoacorus (Yellow Flag), Phalaris arundinacea (Reed Canarygrass), and Microstegium vimineum (Japanese Stiltgrass); browsing by Odocoileus virginianus (White-tailed Deer); residential development; hydrologic changes to wetlands; and climate change.