Polemoniaceae, the Polemonium Family
Herbs with alternate or opposite leaves and conspicuous regular flowers; sepals 5, united; petals 5, united and bearing the 5 stamens in the corolla-tube; ovary superior, 3-celled.
| 1a. Leaves pinnately compound and alternate (2-4 dm. high; flowers blue, in spring) | Greek Valerian, Polemonium reptans. |
| 1b. Leaves fascicled, narrowly linear (about 1 dm. high; flowers pink-purple, in spring) | Moss Pink, Phlox subulata. |
| 1c. Leaves simple, strictly opposite — 2. | |
| 2a. Corolla-lobes deeply 2-cleft to the middle (1-2 dm. high; flowers pink, in spring) | Cleft Phlox, Phlox bifida. |
| 2b. Corolla-lobes entire and rounded, or somewhat notched at the apex — 3. | |
| 3a. Flowers in summer (8-15 dm. high; flowers purple) | Garden Phlox, Phlox paniculata. |
| 3b. Flowers in spring (3-6 dm. high) — 4. | |
| 4a. Corolla blue-purple; stems ascending | Sweet William, Phlox divaricata. |
| 4b. Corolla pink or red-purple; stems erect | Sweet William, Phlox pilosa. |