Hypericaceae, the St. John’s-wort Family
Herbs or shrubs, with opposite entire leaves dotted with translucent glands; flowers usually yellow (or pink); sepals and petals each 5; stamens 5 to many; ovary with 3-5 styles. (St. John’s-wort.)
| 1a. Shrubs (4-8 dm. high; flowers yellow, summer) — 2. | |
| 1b. Herbs (flowers in summer) — 3. | |
| 2a. Styles 5 | St. John’s-wort, Hypericum kalmianum. |
| 2b. Styles 3 | St. John’s-wort, Hypericum prolificum. |
| 3a. Flowers pinkish, 15 mm. broad (3-5 dm. high, in swamps) | Marsh St. John’s-wort, Hypericum virginicum. |
| 3b. Flowers yellow — 4. | |
| 4a. Flowers about 4 cm. wide; principal leaves 5-10 cm. long (7-15 dm. tall) | St. John’s-wort, Hypericum ascyron. |
| 4b. Flowers 8-25 mm. wide; stamens 15 or more — 5. | |
| 4c. Flowers 1-10 mm. wide; stamens 12 or fewer (1-6 dm. high) — 7. | |
| 5a. Petals dotted with black (4-8 dm. high) — 6. | |
| 5b. Petals without black dots (2-5 dm. high) | St. John’s-wort, Hypericum ellipticum. |
| 6a. Flowers 20-25 mm. wide; leaves of an oblong type, broadest near the middle | St. John’s-wort, Hypericum perforatum. |
| 6b. Flowers 10-15 mm. wide; leaves of an ovate type, broadest below the middle | St. John’s-wort, Hypericum punctatum. |
| 7a. Leaves minute, subulate, 1-3 mm. long | Pineweed, Hypericum gentianoides. |
| 7b. Leaves linear, with 1-3 principal veins, broadest near or above the middle | St. John’s-wort, Hypericum canadense. |
| 7c. Leaves lanceolate, 4-6 times as long as broad, with 5-7 principal veins | St. John’s-wort, Hypericum majus. |
| 7d. Leaves oblong, elliptic, or ovate, 1.5-3 times as long as broad — 8. | |
| 8a. Uppermost bracts linear | St. John’s-wort, Hypericum mutilum. |
| 8b. Uppermost bracts resembling the leaves in shape, but smaller | St. John’s-wort, Hypericum boreale. |