Campanulaceae, the Bellflower Family
Herbs with alternate simple leaves and milky juice; sepals 5; petals 5, united; stamens 5, attached at the very base of the corolla; ovary inferior.
| 1a. Stem-leaves circular or nearly so, cordate-clasping at base (2-6 dm. high; flowers blue, axillary, in summer) | Venus’ Looking-Glass, Specularia perfoliata. |
| 1b. Stem-leaves linear or nearly so, not over 1 cm. wide (summer) — 2. | |
| 1c. Stem-leaves ovate to lanceolate, 2 cm. wide or more (flowers blue, in a terminal spike or raceme, summer) (Bellflower) — 4. | |
| 2a. Stem and leaves glabrous (or rarely pubescent) (1-6 dm. high; flowers blue) | Harebell, Campanula rotundifolia. |
| 2b. Stem and leaves rough with reflexed bristles (marsh plants, with weak slender stems 3-10 dm. long; flowers white or pale-blue) (Marsh Bellflower) — 3. | |
| 3a. Corolla 5-8 mm. long | Marsh Bellflower, Campanula aparinoides. |
| 3b. Corolla 10-12 mm. long | Marsh Bellflower, Campanula uliginosa. |
| 4a. Corolla rotate; flowers in spikes (6-15 dm. high) | Bellflower, Campanula americana. |
| 4b. Corolla bell-shape; flowers in one-sided racemes (4-10 dm. high) | Bellflower, Campanula rapunculoides. |