| scientific name | common name(s) | image gallery |
| Achillea millefolium | Common yarrow Yarrow Milfoil Western yarrow | |
| Acer negundo | Ash-leaf maple Ash-leaved maple Box elder Boxelder Fresno de guajuco | |
| Acer pensylvanicum | Striped maple | |
| Acer rubrum | Red maple | |
| Acer saccharum | Sugar maple | |
| Aesculus pavia | Scarlet Buckeye Red buckeye | |
| Ageratina altissima var. altissima | White snakeroot | |
| Amelanchier arborea | Common serviceberry Downy serviceberry Shadbush Juneberry | |
| Amsonia tabernaemontana | Eastern bluestar Blue dogbane Willow amsonia Woodland bluestar | |
| Aquilegia canadensis | Eastern red columbine Wild red columbine | |
| scientific name | common name(s) | image gallery |