The Lime Pond Preserve is an approximately 419-acre tract of rolling terrain surrounding Lime Pond in the town of Columbia, in northern New Hampshire's Coos County. Permanently conserved in 2020 by donation to The Nature Conservancy, the pond, nearby wetlands and surrounding forests have long been considered botanically significant locales owing largely to the presence of calcareous habitats that are generally rare across New Hampshire. There is also a rich collection history spanning nearly 170 years. Dozens of botanists have visited the area, including many regionally prominent figures, resulting in nearly 300 vouchers collected since 1855, and including collections made in almost every decade since 1900.

This annotated flora checklist was produced as part of a floristic study and ecological assessment of the Preserve, envisioned and funded by Tanya Tellman, the long-time steward and conservator of the property. It is compiled from several data sources, including specimen records, reports in Pease (1964) A Flora of Northern New Hampshire, the New Hampshire Natural Heritage Bureau (NHNHB) database, unpublished reports by other contemporary botanists (particularly S. Bailey, J. Hoy, D. Sperduto, and M. Ward), as well as the author’s field observations from 2019-2021. Additional contextual information is available in a separate Flora checklist document (Peters 2022a) and in Ecological Assessment reports for the Preserve (Peters 2021, 2022b).

The known vascular flora of the Lime Pond Preserve contains 442 species of 240 genera in 78 families. The five most speciose families are Cyperaceae, Asteraceae, Poaceae, Rosaceae, and Orchidaceae, representing 42% of the flora. About 15% (67 species) of the flora are naturalized (non-native) species. Thirty-five species (8%) are currently considered of conservation concern with some level of tracking by the New Hampshire Natural Heritage Bureau, and three are considered Regionally Rare in Flora Conservanda, underscoring the botanical importance of the area. All but 28 (6%) of the species have been observed within the past 30 years, and the majority were seen during this study. Of the 28 historical species, at least half are likely still present but were overlooked or not effectively surveyed (e.g., aquatics), while the others, particularly species from the marly pond shore or cedar swamps, may truly have been lost due to human habitat alteration or other factors. Based on the abundance categories presented here (defined below), 10% (44) of the species are common on the Preserve, 22% (97) are frequent, 34% (150) are occasional, and 27% (121) are rare (excluding the 6% historical).

The Consortium of Northeastern Herbaria (CNH) portal is the principal source of specimen data, as well as hosting this digital checklist version of this flora, which links detailed specimen records to the checklist entries. The Southeast Regional Network of Expertise and Collections (SERNEC) portal provided 12 additional specimen records. These portals provide access to far more herbaria than could reasonably be searched manually, yielding nearly 300 records from 16 herbaria (though most are housed at NEBC, GH, NHA, and KESC). Early collections from the area date to 1855 (Boott), followed by more substantial efforts by Arthur Stanley Pease (1907 and later), A.R. Hodgdon, D.E. Boufford and others. Within the portals, both geospatial and text-based searches were used to locate relevant records, and search results were reviewed late in the project to capture as many records as possible from the rapidly evolving universe of digital specimen data. iNaturalist observations for the area were reviewed but did not result in any further additions to the flora. Additional specimens were graciously provided for review by Dan Sperduto, from his personal herbarium.

In compiling this flora checklist I have erred on the side of inclusiveness, generally including unvouchered reports unless I had specific evidence for excluding them. I personally observed all taxa unless specifically noted otherwise, and abundance codes are based on my own observations.

Each checklist entry in the flora follows a standard format:

Scientific name with author

(English name), [=Recent synonym(s)], Abundance code, Occurrence Notes, Collection status (if vouchered), Rarity status (if any)

Scientific (Latin) Name: Typically following Gilman (2015) New Flora of Vermont, Haines (2019) Tracheophyte Checklist of New England, and/or Haines (2011) Flora Novae Angliae, the current regional treatments.

English (Common) Name: Typically following Gilman (2015) and/or Haines (2011).

Recent synonym(s): Provided for taxa with recent changes or major reassignments.

Abundance code: C= Common, F= Frequent, O= Occasional, R= Rare, H= Historical (no reports in past 30 years (i.e., since 1991). These represent a loosely exponential series of gradations that are intended to convey the frequency of encountering a species, thus they integrate the known or apparent population size and extent and, for restricted species, the number of discrete patches. In some cases, split categories (e.g., O/R) are used indicating uncertainty or intermediate status. These terms are necessarily imprecise and based solely on my own observations and recollections, with all their attendant limitations, except as noted otherwise.

Occurrence Notes: A terse description of occupied habitats and distribution on the Preserve, drawing mainly on my own observations, as well as specimen data and other reports. For some rare and historical taxa population size and voucher information is included. Taxonomic comments are also occasionally made here.

Collections: Vouchered taxa are indicated by the abbreviation “COLL.” (collected), with the caveat that some specimens in private collections are not included. Note that most specimen data, often including high resolution specimen images, can be accessed via the digital checklist version of this flora available through the CNH portal at the URL address noted above.

Rarity Status: When applicable, current conservation status and rarity ranks are given for taxa of concern at the state and regional levels. These follow the New Hampshire Natural Heritage Bureau (NHNHB 2020, Nichols pers. comm.) for state ranks and the 2012 Flora Conservanda list (Brumback and Gerke 2013) for taxa designated “Regionally Rare”. SH = Historical and ‘Endangered’, S1 = Critically Imperiled and ‘Endangered’, S2 = Imperiled and ‘Threatened’, S3 = Vulnerable and ‘Watch Listed’, SU = Uncertain (and possibly rare), thus ‘Indeterminate’. Indeterminate status is often related to recent taxonomic shifts (e.g., ‘splitting’) that create uncertainty in a species rarity status.