| Family | Scientific Name | Common Name | Habitat | Distribution | Image |
|---|
| Caprifoliaceae | Triosteum angustifolium var. angustifolium | Smooth Lesser Horse-gentian | Mesic forests, bluffs, outcrops, especially over calcareous or mafic rocks. | CT west to ON and MO, south to NC, nw. GA (Jones & Coile 1988), AL, and LA. | 
|
| Caprifoliaceae | Triosteum angustifolium var. eamesii | Hairy Lesser Horse-gentian | Mesic forests, bluffs, outcrops, especially over calcareous or mafic rocks. | CT and NJ south to NC. | |
| Caprifoliaceae | Triosteum aurantiacum var. aurantiacum | Orange-fruited Horse-gentian | Woodlands and forests in circumneutral soils, particularly those over mafic or calcareous rocks. | QC west to MN, south to GA, KY, and OK; other varieties are more restricted and midwestern or northern in distribution. | 
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| Caprifoliaceae | Triosteum aurantiacum var. glaucescens | | Woodlands and forests in circumneutral soils, particularly those over calcareous rocks or substrate. | NY and Pa west to IN. | |
| Caprifoliaceae | Triosteum aurantiacum var. illinoense | Illinois Horse-gentian | Woodlands and forests in circumneutral soils, particularly those over mafic or calcareous rocks. | PA west to w. IA and se. NE, south to WV, c. KY, AR, and e. OK. | 
|
| Caprifoliaceae | Triosteum perfoliatum | Perfoliate Horse-gentian | Woodlands and forests in circumneutral soils, particularly those over mafic or calcareous rocks. | MA west to MN, south to n. SC, n. GA (Jones & Coile 1988), and OK. | 
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