s none, or else very small and inconspicuous
=Water Milfoil, Myriophyllum tenellum.=

1b. Leaves alternate (1-4 dm. high)
=Mermaid Weed, Proserpinaca palustris.=

1c. Leaves opposite or whorled --2.

2a. Leaves entire (2-4 dm. high) =Mare's-tail, Hippuris vulgaris.=

2b. Leaves toothed or dissected (Water Milfoil) --3.

3a. Flowers in the axils of foliage leaves --4.

3b. Flowers in terminal spikes, subtended by bracts --5.

4a. Flowers above water, subtended by toothed or entire leaves
=Water Milfoil, Myriophyllum heterophyllum.=

4b. Flowers submerged, subtended by dissected leaves
=Water Milfoil, Myriophyllum farwellii.=

5a. Flowers solitary or in pairs at each joint of the spike
=Water Milfoil, Myriophyllum alternifolium.=

5b. Flowers several at each joint of the spike --6.

6a. Bracts deeply pinnatifid
=Water Milfoil, Myriophyllum verticillatum var. pectinatum.=

6b. Bracts entire or toothed
=Water Milfoil, Myriophyllum spicatum.=

ARALIACEAE, the Sarsaparilla Family

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