| | 1. Ovary partly inferior; inflorescences terminal racemes |
| SAMOLUS (no key) |
| | 1' Ovary superior; inflorescences generally not terminal racemes |
| |
| | 2. Inflorescence scapose, ending in an umbel |
| |
| | 3. Corolla lobes reflexed, tips acute to obtuse |
| DODECATHEON |
| | 3' Corolla lobes spreading or erect, tips notched or obcordate |
| |
| ANDROSACE |
| PRIMULA (no key) |
| | 2' Flowers generally in leaf axils |
| |
| | 5. Leaves alternate (except lowest); corolla < calyx |
| CENTUNCULUS (no key) |
| | 5' Leaves opposite or whorled; corolla, if present, = or > calyx |
| |
| | 6. Leaves mainly in a single whorl at stem tip |
| TRIENTALIS |
| | 6' Leaves distributed along stem |
| |
| | 7. Corolla 0, calyx petal-like; flowers solitary and ± sessile, in leaf axils |
| GLAUX (no key) |
| | 7' Corolla present, calyx not petal-like; flowers solitary and pedicelled or in racemes or panicles, in leaf axils |
| |
| | 8. Corolla salmon or blue; fruit circumscissile; annual |
| ANAGALLIS (no key) |
| | 8' Corolla yellow; fruit with valves; perennial herb |
| LYSIMACHIA
|