September 2021 Plant of the Month
Persicaria hydropiperoides (Michx.) Small
False water-pepper smartweed or mild water-pepper
The September Plant of the Month is a native, perennial aptly named water pepper smartweed. This plant is a member of the Smartweed family, the Polygonaceae. New Jersey is home to many smartweed species, both native and introduced. Our Plant of the Month is found throughout North America. The genus was formerly named Polygonum, a synonym today for Persicaria. The genus Polygonum is now used for a small subset of the earlier taxonomic grouping. Persicaria hydropiperoides is widespread in New Jersey. Mary Hough’s New Jersey Wild Plants (1983) identifies this species as one of our most abundant. Only the urban Hudson River counties do not have voucher records.
False water pepper is an obligate wetland species (OBL), and is always found around lakes, ponds, bogs and other bodies of water. The name, P. hydropiperoides is an acknowledgement of a similarity to the annual, introduced Persicaria hydropiper. The false water pepper is a perennial with extensive creeping narrow rootstocks (Fernald, 1950), whereas P. hydropiper is an annual without the branching rootstock. The monthly photo shows September’s plant on a flooded cranberry bog where it forms part of the surrounding open water’s edge flora. It differs from is closest similar species, Persicaria setaceum, by the length of the ocreae bristles.
The plants once in the old genus Polygonum were often used by Native American for a variety of uses. Most often smartweeds were used for a drug, including analgesic and gastrointestinal aids (Moerman, 1998). Moerman’s records curiously do not include the native P. hydropiperoides, but lists P. hydropiper with historic uses. This is suspect and may reflect the lack of correct specific identifications. The Plant of the Month can be seen on acidic ponds and lake edges from now until first frost.