Herbs or thorny shrubs, with alternate or whorled leaves, and small flowers in umbels; sepals 5, minute; petals and stamens each 5; ovary inferior, with 2-5 styles, ripening into a berry.
| 1a. Leaves simple, palmately lobed (thorny shrub; flowers greenish-white, in panicles, in June) | Devil's Club, Fatsia horrida. |
| 1b. Leaves once compounded, whorled (umbel one, terminal) [— 2.] | |
| 1c. Leaves twice or thrice compounded (umbels several) [— 3.] | |
| 2a. Leaflets sessile; flowers white, in spring (1-2 dm. high) | Dwarf Ginseng, Panax trifolium. |
| 2b. Leaflets stalked; flowers greenish, in summer (2-5 dm. high) | Ginseng, Panax quinquefolium. |
| 3a. Stem and petioles spiny or bristly (flowers white, summer) [— 4.] | |
| 3b. Stem and petioles smooth or a little pubescent (flowers greenish-white) [— 5.] | |
| 4a. Shrubby, with stout thorns (1-3 m. high) | Hercules' Club, Aralia spinosa. |
| 4b. Herbaceous, with slender bristles (4-10 dm. high) | Bristly Sarsaparilla, Aralia hispida. |
| 5a. Stem-leaves present; leaflets cordate at the base (8-15 dm. high; summer) | Spikenard, Aralia racemosa. |
| 5b. Leaf and flower-stalk arising from the ground; leaflets acute at the base (2-4 dm. high; spring) | Wild Sarsaparilla, Aralia nudicaulis. |
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. |
CORNACEAE, the Dogwood Family
Trees, shrubs, or herbs, with alternate leaves and small flowers in rather crowded rounded or flattened clusters; sepals 4, minute; petals and stamens each 4; ovary inferior, ripening into a berry. In one genus the flowers are minute and greenish, with 5 sepals and petals minute or none.
| 1a. Leaves alternate [— 2.] | |
| 1b. Leaves opposite [— 3.] | |
| 2a. Flowers white, conspicuous, in flattened clusters (shrubs 2-4 m. high; flowers in late spring) | Dogwood, Cornus alternifolia. |
| 2b. Flowers greenish, inconspicuous, in small axillary clusters (tree; flowers in spring) | Sour Gum, Nyssa sylvatica. |
| 3a. Flower clusters small and dense, surrounded by a showy involucre of 4 bracts, resembling a corolla of 4 petals [— 4.] | |
| 3b. Flowers in open flattened clusters, without petal-like involucre (shrubs 1-4 m. high; late spring) [— 5.] | |
| 4a. Herbaceous, 3 dm. high or less (flowers in late spring) | Dwarf Dogwood, Cornus canadensis. |
| 4b. Tall shrub or tree (flowers in late spring) | Flowering Dogwood, Cornus florida. |
| 5a. Leaves distinctly pubescent beneath with woolly or spreading hairs [— 6.] | |
| 5b. Leaves smooth beneath, or pubescent with short appressed hairs [— 9.] | |
| 6a. Leaves rough above; fruit white | Dogwood, Cornus asperifolia. |
| 6b. Leaves smooth or finely soft-hairy above [— 7.] | |
| 7a. Leaves at least twice as long as wide; branches brownish or purplish [— 8.] | |
| 7b. Leaves less than twice as long as wide; branches greenish; fruit blue | Dogwood, Cornus circinata. |
| 8a. Branches purplish; fruit blue | Dogwood, Cornus amomum. |
| 8b. Branches brownish; fruit white | Dogwood, Cornus baileyi. |
| 9a. Branches bright red or reddish-purple | Dogwood, Cornus stolonifera. |
| 9b. Branches grayish | Dogwood, Cornus paniculata. |
ERICACEAE, the Heath Family
Herbs or shrubs, frequently with evergreen leaves; sepals 4-5; corolla regular, with 4-5 petals; stamens as many or twice as many; ovary 3-10-celled, with 1 style.