Umbelliferae, the Parsley Family
Herbs, with alternate, usually compound leaves, the petioles dilated at the base; flowers small, in umbels or heads; sepals 5, minute or even wanting; petals and stamens each 5; ovary inferior, with 2 styles, ripening into a dry fruit.
| 1a. Leaves simple (flowers in summer) — 2. | |
| 1b. Leaves compound, or at least deeply cleft — 4. | |
| 2a. Leaves linear, sword-shape (4-10 dm. tall; flowers greenish-white) | Rattlesnake Master, Eryngium yuccifolium. |
| 2b. Leaves kidney-shape or almost circular (stems creeping, about 1 dm. high; flowers white) (Water Pennywort) — 3. | |
| 3a. Leaves peltate, attached by the center | Water Pennywort, Hydrocotyle umbellata. |
| 3b. Leaves not peltate, attached by the margin | Water Pennywort, Hydrocotyle americana. |
| 4a. Flowers yellow or purple — 5. | |
| 4b. Flowers white or greenish — 13. | |
| 5a. Leaf-segments entire (4-8 dm. high) — 6. | |
| 5b. Leaf-segments toothed or incised — 7. | |
| 6a. Leaf-segments filiform (summer) | Fennel, Foeniculum vulgare. |
| 6b. Leaf-segments ovate to lanceolate | Golden Alexander, Taenidia integerrima. |
| 7a. Leaves pinnately compound; some of the leaflets incised or pinnatifid — 8. | |
| 7b. Leaves ternately compound; the segments crenate or serrate — 9. | |
| 7c. Leaves deeply palmately cleft or divided; flowers in head-like umbels — 18a. | |
| 8a. Leaf-segments obtuse, rounded, or cordate at the base (6-15 dm. high; summer) | Wild Parsnip, Pastinaca sativa. |
| 8b. Leaf-segments narrowed to the base (4-8 dm. high; spring) | Prairie Parsley, Polytaenia nuttallii. |
| 9a. Terminal leaflets conspicuously stalked, their total length, including stalk, at least 50% greater than the length of the lateral leaflets (Meadow Parsnip) — 10. | |
| 9b. Terminal leaflets not conspicuously stalked, their total length, including stalk, about equaling the lateral leaflets (4-8 dm. high; late spring) (Golden Alexander) — 12. | |
| 10a. Flowers purple (4-8 dm. high; early summer) | Meadow Parsnip, Thaspium aureum var. atropurpureum. |
| 10b. Flowers yellow — 11. | |
| 11a. Stem-leaves once-ternate; leaflets finely serrate (4-8 dm. high; early summer) | Meadow Parsnip, Thaspium aureum. |
| 11b. Many stem-leaves 2-3-ternate; leaflets coarsely serrate or incised (6-12 dm. high; early summer) | Meadow Parsnip, Thaspium barbinode. |
| 12a. Basal and lower stem-leaves 2-3-ternate | Golden Alexander, Zizia aurea. |
| 12b. Basal leaves simple; stem-leaves once-ternate | Golden Alexander, Zizia cordata. |
| 13a. Leaves once-pinnate (or the submerged leaves decompound, if present) (summer) — 14. | |
| 13b. Leaves ternately, palmately, or 2-3-pinnately compound — 16. | |
| 14a. Leaflets mostly ovate or ovate-lanceolate, some of them coarsely incised (3-9 dm. high) | Water Parsnip, Berula erecta. |
| 14b. Leaflets linear to oblong, serrate to nearly entire, not incised (6-15 dm. high) — 15. | |
| 15a. Leaflets entire, or with a few low remote teeth | Cowbane, Oxypolis rigidior. |
| 15b. Leaflets finely but sharply serrate | Water Parsnip, Sium cicutaefolium. |
| 16a. Leaves principally basal, decompound; flowers in early spring (1-2 dm. high) | Harbinger of Spring, Erigenia bulbosa. |
| 16b. Leaves principally on the stem — 17. | |
| 17a. Leaves palmately or ternately once-compound — 18. | |
| 17b. Leaves 2-3 times compound or decompound — 24. | |
| 18a. Flowers short-pedicelled, crowded in head-like umbels, greenish; ovary bristly (4-9 dm. high; early summer) (Black Snakeroot) — 19. | |
| 18b. Flowers in open umbels, white — 22. | |
| 19a. Styles short, not projecting beyond the bristles of the mature fruit — 20. | |
| 19b. Styles long, projecting beyond the bristles of the fruit, and recurved — 21. | |
| 20a. Staminate flowers on pedicels 3-4 mm. long, equaling or barely exceeding the fruit | Black Snakeroot, Sanicula trifoliata. |
| 20b. Staminate flowers short-pedicelled, concealed among the fruits | Black Snakeroot, Sanicula canadensis. |
| 21a. Fruit short-stalked, 4 mm. long or less | Black Snakeroot, Sanicula gregaria. |
| 21b. Fruit sessile, 6-7 mm. long | Black Snakeroot, Sanicula marilandica. |
| 22a. Umbel unsymmetrical, its branches irregular in length; plant slender (3-8 dm. tall; early summer) | Honewort, Cryptotaenia canadensis. |
| 22b. Umbel symmetrical with regular branches; plants tall and stout — 23. | |
| 23a. Stem and leaves very pubescent (10-25 dm. high; summer) | Cow Parsnip, Heracleum lanatum. |
| 23b. Stem and leaves glabrous or nearly so (5-15 dm. high; early summer) | Masterwort, Imperatoria ostruthium. |
| 24a. Ovary and fruit bristly (4-10 dm. high) — 25. | |
| 24b. Ovary and fruit smooth or winged, never bristly — 27. | |
| 25a. Umbels loose, open, few-flowered; woodland plants blooming in spring (Sweet Cicely) — 26. | |
| 25b. Umbels densely flowered; weedy plants blooming from summer to fall | Wild Carrot, Daucus carota. |
| 26a. Stem villous-pubescent | Sweet Cicely, Osmorhiza claytoni. |
| 26b. Stem glabrous except at the joints | Sweet Cicely, Osmorhiza longistylis. |
| 27a. Leaflets merely serrate (flowers in summer) — 28. | |
| 27b. Leaflets coarsely incised, so that the leaf appears dissected — 30. | |
| 28a. Umbel densely pubescent (8-15 dm. high) | Angelica, Angelica villosa. |
| 28b. Umbel smooth — 29. | |
| 29a. Leaf-segments broadly ovate (8-15 dm. high) | Angelica, Angelica atropurpurea. |
| 29b. Leaf-segments lanceolate (8-15 dm. high) | Water Hemlock, Cicuta maculata. |
| 29c. Leaf-segments linear (4-10 dm. high) | Water Hemlock, Cicuta bulbifera. |
| 30a. Principal branches of the umbel 2-5; fruit linear-oblong; woodland plants blooming in spring (2-4 dm. high) | Chervil, Chaerophyllum procumbens. |
| 30b. Principal branches of the umbel 7 or more; fruit ovate to broadly elliptical (summer) — 31. | |
| 31a. Native plants, growing in swamps (5-15 dm. high) | Hemlock Parsley, Conioselinum chinense. |
| 31b. Introduced plants, in waste places and along roads — 32. | |
| 32a. Stems conspicuously spotted with purple (5-15 dm. high) | Poison Hemlock, Conium maculatum. |
| 32b. Stems not spotted with purple (2-5 dm. high) | Caraway, Carum carvi. |