90a. Twining vine (flowers white, summer) =Hemp Weed, Mikania scandens.= 90b. Not twining or climbing --91. 91a. Involucral bracts deeply fringed at the tip (flowers purple, blue, or rarely white, summer; 3-6 dm. high) --92. 91b. Involucral bracts entire or nearly so --93. 92a. Upper leaves linear or narrowly lanceolate =Corn Flower, Centaurea cyanus.= 92b. Upper leaves oblong or oblong-lanceolate =Knapweed, Centaurea nigra.= 93a. Pappus none or a short ring or crown (5-10 dm. high; flowers yellow, summer) =Costmary, Chrysanthemum balsamita var. tanacetoides.= 93b. Pappus of 2-4 stiff awns (2-15 dm. high; flowers yellow, late summer) (Bur Marigold) --130. 93c. Pappus of hairs or bristles --94. 94a. Leaves linear or narrowly lanceolate, entire; heads never in a large flat-topped cluster --95. 94b. Leaves not linear --99. 95a. Heads showy, purple, in a long spike or raceme (late summer) (Blazing Star) --96. 95b. Heads not showy, in a loose panicle or raceme --240b. 96a. Involucral bracts rounded at the tip, appressed (5-15 dm. high) --97. 96b. Involucral bracts pointed (3-6 dm. high) --98. 97a. Heads 8-12-flowered =Blazing Star, Liatris spicata.= 97b. Heads with 25 flowers or more =Blazing Star, Liatris scariosa.= 98a. Involucral bracts long-acuminate, spreading =Blazing Star, Liatris squarrosa.= 98b. Involucral bracts mucronate, appressed =Blazing Star, Liatris cylindracea.= 99a. Flowers yellow (2-8 dm. high) --172b. 99b. Flowers bright-red or purple, in flat-topped clusters (8-20 dm. high; late summer) (Ironweed) --100. 99c. Flowers blue (3-8 dm. high; late summer) =Mist Flower, Eupatorium coelestinum.= 99d. Flowers flesh-color, pink, cream-color, or white (flowers in summer) --103. 100a. Leaves glabrous beneath or minutely pubescent; heads 15-30-flowered --101. 100b. Leaves tomentose beneath; heads 30-50-flowered --102. 101a. Inflorescence densely crowded; usually 1 m. or less high =Ironweed, Vernonia fasciculate.= 101b. Inflorescence loose and open, 15-30 cm. wide; 1-2 m. high =Ironweed, Vernonia altissima.= 102a. Pappus tawny in color =Ironweed, Vernonia missurica.= 102b. Pappus purple =Ironweed, Vernonia illinoensis.= 103a. Leaves alternate --104. 103b. Leaves opposite --106. 103c. Leaves whorled (1-3 m. high; flowers pink or purple, late summer) (Joe-Pye Weed) --107. 104a. Heads 5-flowered (5-20 dm. high; flowers white or pinkish, late summer) (Indian Plantain) --105.