5a. Leaves deeply dentate or pinnatifid (2-5 dm. high; early summer) =Evening Primrose, Oenothera laciniata.= 5b. Leaves entire or undulate or finely toothed (5-12 dm. high; summer) --6. 6a. Hairs on the stem with broad reddish bases =Evening Primrose, Oenothera muricata.= 6b. Hairs on the stem none, or without swollen bases --7. 7a. Stem and foliage glabrous, or with sparse spreading hairs =Evening Primrose, Oenothera biennis.= 7b. Stem and foliage densely but closely appressed-pubescent =Evening Primrose, Oenothera rhombipetala.= 8a. Petals 5-10 mm. long =Sundrops, Oenothera pumila.= 8b. Petals 14 mm. long or more =Sundrops, Oenothera fruticosa.= 9a. Petals 2, reverse heart-shape, stamens 2 (flowers small, white, summer) (Enchanter's Nightshade) --10. 9b. Petals 4; stamens 4 or 8 --12. 10a. Leaves rounded at the base, denticulate (3-8 dm. high; fruit prickly) =Enchanter's Nightshade, Circaea lutetiana.= 10b. Leaves cordate at the base --11. 11a. Fruit 2-celled, bristly (2-4 dm. high) =Enchanter's Nightshade, Circaea intermedia.= 11b. Fruit 1-celled, with soft hairs (delicate plant 2 dm. high, or less) =Enchanter's Nightshade, Circaea alpina.= 12a. Petals entire (summer) --13. 12b. Petals notched at the end (flowers white or pinkish, less than 1 cm. broad, in summer) (Willow Herb) --15. 13a. Flowers 2-3 cm. wide, purple (7-20 dm. high) =Fireweed, Epilobium angustifolium.= 13b. Flowers about 1 cm. wide --14. 14a. Flowers red (2-5 dm. high) =Gaura, Gaura coccinea.= 14b. Flowers white, turning pink when old =Gaura, Gaura biennis.= 15a. Leaves entire, the margins usually somewhat revolute --16. 15b. Leaves toothed, flat (4-9 dm. high) --18. 16a. Plant densely pubescent with spreading hairs (3-8 dm. high) =Willow Herb, Epilobium molle.= 16b. Plant pubescent with appressed or incurved hairs --17. 17a. Leaves linear, the margin revolute (3-5 dm. high) =Willow Herb, Epilobium densum.= 17b. Leaves narrowly lanceolate, not revolute (2-4 dm. high) =Willow Herb, Epilobium palustre.= 18a. Seeds tipped with a tuft of reddish-brown hairs =Willow Herb, Epilobium coloratum.= 18b. Seeds tipped with a tuft of white hairs =Willow Herb, Epilobium adenocaulon.= HALORAGIDACEAE, the Water Milfoil Family Aquatic or marsh herbs, with alternate, opposite, or whorled leaves, and small, inconspicuous terminal or axillary flowers, frequently without petals (summer).