Rare Native Plants
NH Natural Heritage Bureau maintains records on approximately 400 plant species judged to be endangered or threatened under the Native Plant Protection Act. The tracking list was originally developed in cooperation with professional and amateur botanists, conservation organizations, and other knowledgeable individuals. Plants tracked by NH Natural Heritage are those with state ranks of S1 or S2 (see Rarity & Ranking for detailed descriptions). Range-wide distribution maps, state and provincial ranks, and other information on the status of all plants and animals in North America can be found at the web site www.natureserve.org maintained by NatureServe.
Native Plant Protection Act
In 1987, the New Hampshire state legislature passed the Native Plant Protection Act (RSA 217-A) and formally recognized that "for human needs and enjoyment, the interests of science, and the economy of the state, native plants throughout this state should be protected and conserved; and…their numbers should be maintained and enhanced to insure their perpetuation as viable components of their ecosystems for the benefit of the people of New Hampshire." To compile a list of the species requiring protection, NH Natural Heritage collaborates with knowledgeable botanists and identifies the most imperiled taxa as "endangered" and those likely to become endangered as "threatened." Approximately 400 taxa are listed. See definitions below:
Endangered (E): A native plant taxon at very high risk of extirpation in the state due to very restricted range, very few populations (often though not always five or fewer observed within the last 20 years), very steep declines, severe threats, or other factors. A historical rare native plant taxon is one that has not been observed in the state in over 20 years. It is considered endangered unless there is credible evidence that all previously known populations of the taxon in the state have been extirpated.
Threatened (T): A native plant taxon at high risk of extirpation in the state due to restricted range, few populations (often though not always between six to twenty observed within the last 20 years), steep declines, severe threats, or other factors.
Four of these species are also listed as endangered or threatened under the federal Endangered Species Act. These plants are: Jesup's milk-vetch (Astragalus robbinsii var. jesupii), small whorled pogonia (Isotria medeoloides), Robbin's cinquefoil (Potentilla robbinsiana), and northeastern bulrush (Scirpus ancistrochaetus).
Our nomenclature and taxonomic treatment of New Hampshire plants follow Arthur Haines' Tracheophyte Checklist of New England: http://www.arthurhaines.com/tracheophyte-checklist/.