| Family | Scientific Name | Common Name | Habitat | Distribution | Image |
|---|---|---|---|---|---|
| Hypericaceae | Triadenum fraseri | Fraser’s Marsh St. John's-wort | Bogs, peaty wetlands, seepage swamps. | NL (Newfoundland) and QC west to MN, south to NY, PA, w. VA, ne. TN, w. NC, OH, n. IN, and NE. |  |
| Hypericaceae | Triadenum tubulosum | Southern Marsh St. John's-wort | Bogs, peaty wetlands, drawdown sloughs along rivers, drawdown shorelines along man-made reservoirs. | Se. VA south to Panhandle FL, west to LA, and north in the interior to se. and c. TN, s. IL and s. OH. |  |
| Hypericaceae | Triadenum virginicum | Common Marsh St. John's-wort | Bogs, fens, tidal swamps and marshes, other peaty wetlands. | NS west to OH and s. ON, south to s. FL and MS, mostly on the Coastal Plain but scattered inland. |  |
| Hypericaceae | Triadenum walteri | Walter’s Marsh St. John's-wort | Swamp forests and marshes. | MD south to n. peninsular FL, west to e. TX, and north in the interior to s. MO, s. IL, and OH. |  |
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