Plantaginaceae, the Plantain Family
Herbs with basal leaves and small white flowers in spikes; sepals 4; petals 4, united; stamens 4; ovary 2-celled.
| 1a. Leaves linear (1-4 dm. high; summer) — 2. | |
| 1b. Leaves broader, lanceolate to broadly ovate or cordate (summer) — 3. | |
| 2a. Spikes mixed with bracts several times longer than the flowers | Buckhorn, Plantago aristata. |
| 2b. Bracts about as long as the flowers | Plantain, Plantago purshii. |
| 3a. Leaves cordate, pinnately veined; plant of wet ground and marshes (4-8 dm. tall) | Plantain, Plantago cordata. |
| 3b. Leaves with 3 to many longitudinal ribs or veins — 4. | |
| 4a. Leaves densely pubescent with grayish hairs — 5. | |
| 4b. Leaves smooth or slightly pubescent — 6. | |
| 5a. Flower-stalks 3-6 dm. high | Plantain, Plantago media. |
| 5b. Flower-stalks less than 3 dm. high | Plantain, Plantago virginica. |
| 6a. Flower-stalks 3-6 dm. high; spikes not over 10 cm. long | English Plantain, Plantago lanceolata. |
| 6b. Scapes 1-4 dm. high; spikes long and slender, usually equaling or longer than the peduncle; dooryard plantains — 7. | |
| 7a. Leaves green at the base | Plantain, Plantago major. |
| 7b. Leaves reddish at the base | Plantain, Plantago rugelii. |