Persicaria robustior (Small) E.P. Bicknell

Persicaria robustior (Small) E.P. Bicknell View in CoL [ Polygonaceae ]

Persicaria robustior is reported as extant in southern Indiana based on a collection made in 2021 (Jackson County) by Scott Namestnik. This collection provides documentation of the occurrence of P. robustior in the Indiana portion of the Flora of the Southeastern United States coverage area, preliminarily reported by Weakley & Southeastern Flora Team (2022a). Plants within the observed population were growing in a fairly dense colony on the margin of an impounded marsh.

Often taxonomically lumped into P.punctata , the true distribution of this rhizomatous and stoloniferous species is probably not well understood. It differs from P. punctata in having wider leaves (often over 2.5 cm wide, especially earlier in the year), less interrupted spike-like racemes, and at least the lower ocreolae in the raceme entire (or nearly so) at their summits (versus being ciliate) ( Wilhelm & Rericha 2017; Weakley & Southeastern Flora Team 2022a). Persicaria robustior generally has a more northern distribution, most frequent in the New England states but extending north into Nova Scotia, Quebec and Ontario, and its distribution extends south along the northern portion of the Atlantic coastal plain, with several counties of occurrence scattered through the eastern United States generally south to Missouri, Kentucky and North Carolina; there are outlier populations in Texas and Florida, the latter of which is treated as a waif ( Kartesz 2015; Weakley & Southeastern Flora Team 2022a). Persicaria robustior is considered globally apparently secure (G4G5) and apparently secure in the United States (N4N5); within the United States, its subnational conservation status ranks range from historical (SH) in Maine and Missouri to critically imperiled (S1) in New Hampshire to imperiled (S2) in New Jersey and Ohio to apparently secure (S4) and secure (S5) in Pennsylvania and New York, respectively ( NatureServe 2023). Several states have not assessed the subnational conservation status rank for this species ( NatureServe 2023). In Indiana, the conservation status of P.robustior is unknown (SU).Prior to 2021, it was considered extirpated from Indiana, with historical records from Porter and Greene counties ( Consortium of Midwest Herbaria 2023). In 2021, Scott Namestnik, Nathanael Pilla and Dominick Pilla rediscovered it in Porter County ( Consortium of Midwest Herbaria 2023), and, as a result, it was moved to state endangered on the list of Endangered, Threatened, and Extirpated Plants of Indiana (IDNR 2022). The occurrence of the species in Jackson County, Indiana represents the only currently known extant population of the species in southern Indiana.

Voucher Specimens: INDIANA. Jackson Co.: Muscatatuck National Wildlife Refuge, on edge of impounded marsh, soil saturated to several inches of inundation,associated species: Carex hyalinolepis , Cephalanthus occidentalis , Juncus effusus , Lemna turionifera , Ludwigia palustris , Ludwigia peploides , Persicaria coccinea , Spirodela polyrhiza , Typha sp. , Wolffia brasiliensis , Wolffia columbiana , 38.94040, –85.81058, 7 Oct 2021, S. Namestnik 5298 (BUT,IND).