Plants and Animals
Persicaria robustior Stout smartweed
Key Characteristics
A rhizomatous, herbaceous perennial that often spreads colonially from the root system forming dense colonies. Leaves are simple, petioled, elliptic-lanceolate, and glabrous with antrorsely-strigose margins. Flowers are green to white comprised of 5 fused tepals spotted with brown glands.
Stout smartweed is the only Persicaria species found in Michigan that has a combination of glabrous stems, appressed ocrea bristles, spotted flowers, a dark and smooth achene, and an uninterrupted inflorescence.
Status and Rank
US Status: No Status/Not Listed
State Status: T - Threatened (legally protected)
Global Rank: G5 - Secure
State Rank: SNR - Not ranked
Occurrences
| County | Number of Occurrences | Year Last Observed |
|---|---|---|
| Clinton | 1 | 2023 |
| Muskegon | 1 | 2023 |
| St. Joseph | 1 | 2022 |
Information is summarized from MNFI's database of rare species and community occurrences. Data may not reflect true distribution since much of the state has not been thoroughly surveyed.
Habitat
Known occurrences in Michigan have only been found in Barry and St. Joseph Counties. Occurrences found in a shrubby and marshy sedge meadow near a fen and in small colonies within the floodplain of a major river.
Natural Community Types
For each species, lists of natural communities were derived from review of the nearly 6,500 element occurrences in the MNFI database, in addition to herbarium label data for some taxa. In most cases, at least one specimen record exists for each listed natural community. For certain taxa, especially poorly collected or extirpated species of prairie and savanna habitats, natural community lists were derived from inferences from collection sites and habitat preferences in immediately adjacent states (particularly Indiana and Illinois). Natural communities are not listed for those species documented only from altered or ruderal habitats in Michigan, especially for taxa that occur in a variety of habitats outside of the state.
Natural communities are not listed in order of frequency of occurrence, but are rather derived from the full set of natural communities, organized by Ecological Group. In many cases, the general habitat descriptions should provide greater clarity and direction to the surveyor. In future versions of the Rare Species Explorer, we hope to incorporate natural community fidelity ranks for each taxon.
Associated Plants
Silver maple (Acer saccharinum), cut-leaved water parsnip (Berula erecta), common dodder (Cuscuta gronovii), cut grass (Leersia oryzoides), common duckweed (Lemna minor), arrow-arum (Peltandra virginica), water smartweed (Persicaria amphibia), bitter dock (Rumex obtusifolius), willow (Salix eriocephala), lizard’s-tail (Saururus cernuus), marsh fern (Thelypteris palustris), pointed water meal (Wolffia brasiliensis), and common water meal (Wolffia columbiana)
Management Recommendations
Management Avoidance Period: From first week of August to first week of October
Survey Methods
Random meander search covers areas that appear likely to have rare taxa, based on habitat and the judgment of the investigator.
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Meander Search
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Survey Period: From first week of August to first week of October
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References
Survey References
- Elzinga, C.L., D.W. Salzer, and J.W. Willoughby. 1998. Measuring and Monitoring Plant Populations. The Nature Conservancy and Bureau of Land Management, Denver. BLM Technical Reference 1730-1. 477pp.
- Goff, G.F., G.A. Dawson, and J.J. Rochow. 1982. Site examination for Threatened and Endangered plant species. Environmental Management 6(4): 307-316
- Nelson, J.R. 1984. Rare Plant Field Survey Guidelines. In: J.P. Smith and R. York. Inventory of rare and endangered vascular plants of California. 3rd Ed. California Native Plant Society, Berkeley. 174pp.
- Nelson, J.R. 1986. Rare Plant Surveys: Techniques For Impact Assessment. Natural Areas Journal 5(3):18-30.
- Nelson, J.R. 1987. Rare Plant Surveys: Techniques for Impact Assessment. In: Conservation and management of rare and endangered plants. Ed. T.S. Elias. California Native Plant Society, Sacramento. 8pp.
Technical References
- Gleason, H. A., and A. Cronquist. 1991. Manual of Vascular Plants of Northeastern United States and Adjacent Canada. 2nd Ed. The New York Botanical Garden, New York, New York.
- Gray, A., and M. L. Fernald. 1950. Gray’s Manual of Botany. 8th ed. American Book Company, New York, New York.
- Hinds, H. R. and C. C. Freeman. 2020. Persicaria robustior. Flora of North America. <https://floranorthamerica.org/Persicaria_robustior>. Accessed 22 September, 2025.
- Kogge, S. and Reznicek, A. A. 2001. AA Reznicek 11291. MICH: Angiosperms 1001979. U.S.A., Michigan. Barry County.
- Michigan Natural Features Inventory (MNFI). 2025. Michigan Natural Heritage Database, Lansing, MI.
- Reznicek, A. A., E. G. Voss, and B. S. Walters. 2011. Michigan Flora Online. University of Michigan. Web. <https://michiganflora.net/>.