The most recent study of rare plants was performed in 1994. The following comes from the “Lamprey River Resource Assessment”, published in 1994.
"One federally listed species, the small whorled pogonia (Isotria medeoloides), one state endangered species, separated sedge (Carex seorsa), and three state threatened species, climbing hempweed (Mikania scandens), blunt cliff-fern (Woodia obtusa), and small beggars tick Bidens discoidea, currently listed but likely to be delisted due to recent finds) were documented in the Lamprey during the 1993-1994 field seasons."
While a full study of flora along the Lamprey rivers has not been undertaken since the mid-1990s, site evaluations for land protection projects often provide glimpses of rare plants. A large project in Epping that was completed in 2011 uncovered a healthy population of NH State Endangered button sedge (Carex bullata). This patch is one of only four known in New Hampshire.