Persicaria densiflora (Meisn.) Moldenk.

Persicaria densiflora (Meisn.) Moldenk. View in CoL [ Polygonaceae ]

Persicaria densiflora is reported as new to Indiana in two counties based on collections made in 2020 (Jefferson County) by Scott Namestnik and Roger Hedge and in 2021 (Jackson County) by Scott Namestnik. These collections provide documentation of the occurrence of P. densiflora in Indiana preliminarily reported by Weakley & Southeastern Flora Team (2022a). The Jefferson County population was found along the margin of the man-made Krueger Lake, forming a dense and robust colony in a zone several meters wide. The Jackson County population was found in an impounded wetland as the dominant vegetation covering several acres in shallow water.

This conspicuous, decumbent smartweed has a scattered distribution within the Mississippi Embayment and along the coastal plain of the southeastern United States, with outlier populations sparsely distributed elsewhere in the southeastern United States ( Kartesz 2015 [as P.glabra ]; Weakley & Southeastern Flora Team 2022a). There is some disagreement in the native range of the species, as Weakley & Southeastern Flora Team (2022a) and Kartesz (2015) consider it introduced in Kentucky and native in Maryland, whereas NatureServe (2023 [as Polygonum densiflorum ]) considers it native in Kentucky and introduced in Maryland; all of these sources treat it as native elsewhere in North America. Subnational conservation status ranks have not been assigned throughout most of its native range, but at its northernmost extent within the Mississippi Embayment in Missouri and Kentucky it is considered critically imperiled (S1S2 and S1?, respectively), at its northernmost extent along the coastal plain in New Jersey it is considered imperiled (S2), in North Carolina and Georgia it is considered vulnerable (S3 and S3?, respectively), in Delaware it is considered apparently secure (S4), and in Virginia it is considered secure (S5); globally P.densiflora is secure (G5), and in the United States it is apparently secure (N4?) ( NatureServe 2023). In Indiana, because it is growing in created wetland conditions, it is being treated as an unnatural introduction and thus will not have a conservation status rank (SNA). It is expected that additional populations of P. densiflora will be found in other southern Indiana counties, as it likely can be spread via waterfowl, as well as on fishing and boating equipment.

Voucher Specimens: INDIANA. Jefferson Co.: Krueger Lake County Park, abundant, rhizomatous colony along margin of Krueger Lake, 38.827683, –85.388828, 23 Sep 2020, S. Namestnik & R. Hedge 4674 (IND, NY). Jackson Co.: Muscatatuck National Wildlife Refuge, in impounded marsh in shallow water, associated species: Cephalanthus occidentalis , Persicaria robustior , Taxodium distichum , Typha sp. , 38.94063, -85.80513, 7 Oct 2021, S. Namestnik 5297 (BUT,IND).