Threatened and Endangered Plant Species
No federal or state listed threatened or endangered plant species was encountered during the survey. However, two species were found which are listed by the NJDEP’s Natural Heritage Program as S2, imperiled; or S3, rare (see below for explanation of ratings):
Several hundred individuals of star duckweed (Lemna trisulca), a minute, free-floating aquatic plant, were found in open water on both Birchwood and Mountain lakes. This species, which has historically been found in some of the northern counties and in one Coastal Plain site, is ranked by the Heritage as an S2 species.
A small population of floating heart (Nymphoides cordata), ranked as an S3 species, was found at Birchwood Lake. This plant, which is a member of the gentian family, has been traditionally thought of as a Coastal Plain species in New Jersey, even though it ranges north to the Canadian Maritimes. A few populations have been discovered recently in Morris and Sussex counties (Radis 1994). Floating heart is listed as a protected plant by the Pinelands Commission.
Neither star duckweed nor floating heart has any legal standing or protected status in northern New Jersey; very few plants do, outside of the Pine Barrens and the Coastal (CAFRA) Zone. They should, however, be taken into consideration if activities such as weed control are considered at Birchwood or Mountain lakes. Control methods such as the use of non-specific herbicides or plant-control fish, both of which can entirely eliminate all vegetation in lakes, would be highly detrimental to the two species.
Heritage Program Ranking Terms (in Snyder 1992)
S1. Critically imperiled in New Jersey because of extreme rarity (5 or few occurrences or very few remaining individuals or acres). Species ranked as S1 are often restricted to specialized habitats and/or restricted to an extremely small (+ or-3%) geographical area of the state. Also included are species which were formerly more abundant, but because of habitat destruction or some other critical factor of its biology, they have been demonstratively reduced in abundance. In essence, these are species for which, even with intensive searching, sizable additional occurrences are unlikely to be discovered
S2. Imperiled in New Jersey because of rarity (6 to 20 occurrences). Historically many of these species may have been more frequent, but now, largely through habitat destruction, are known from fewer extant occurrences. The S2 rank also includes species which occur in habitats restricted to +/- 10% of the total state area.
S3. Rare in NJ with 21 to 50 occurrences. Includes species which are widely distributed in the state but often occurring in small populations, and also in habitats which may be common or widespread. Species having a moderately restricted distribution (but greater than 10%) in New Jersey, but are locally abundant, are also included. Species ranked S3 are not yet imperiled in state but may soon be if additional populations are destroyed.