Northern Prairie Wildlife Research Center
Reference:
Pennell, F. W. 1921. "Veronica" in North and South America.
Rhodora 23:1-22, 29-41.
| Lead | Characteristic | Go To |
| 1 | Racemes terminal; pedicels 2 mm or less long. | V. peregrina |
| 1 | Racemes axillary; pedicels longer than 2 mm. | Lead 2 |
| 2 | Leaves short-petioled. | V. americana |
| 2 | Leaves sessile, often clasping. | Lead 3 |
| 3 | Capsules turgid, slightly notched at the tip; seeds numerous, 0.5 mm or less long; leaves 1.5-5X longer than wide. | Lead 4 |
| 3 | Capsules strongly flattened, conspicuously notched at the tip; seeds 5-9 per locule, 1.2-1.8 mm long; leaves (3)4-20X longer than wide. | V. scutellata |
| 4 | Leaves 1.5-3X longer than wide; corolla blue or violet; capsules about as wide as long. | V. anagallis-aquatica |
| 4 | Leaves (2.5)3-5X longer than wide; corolla white, pink or pale bluish; capsules wider than long. | V. catenata |