172 THE INDIANA WEED BOOK. 



triloba L.) having the stem branched, 2-5 feet high, the lower leaves 

 deeply 3-lobed or 3-divided, the disk egg-shaped, dark purple, the 

 rays 8-12, deep yellow or orange, and the tall or green-headed cone- 

 flower (R. laciniata L.) with the stem 3-12 feet high, the leaves 

 divided into 3-7 toothed or lobed segments, the disk oblong- 

 cylindric, greenish-yellow, and the rays, 6-10, bright yellow. The 

 former grows in low moist meadows and the latter mostly in al- 

 luvial soil along the dense shaded banks of streams. Both are easily 

 killed by repeated mowing or deep cutting. 



141. HELTANTHUS DECAPETALUS L. Wild Sunflower. Thin-leaved Sun- 

 flower. (P. N. 3.) 



Stem slender, glabrous, branched above, 2-5 feet high; leaves thin, 

 ovate, pointed, sharply toothed, roughish above, the lower all opposite, 

 slender-stalked, the upper alternate. Heads numerous, 2-3 inches broad; 

 involucre cup-shaped, its bracts linear-lanceolate, pointed, spreading, often 

 longer than the yellow disk; rays 8-15, light yellow. Achenes thick, 

 somewhat flattened, glabrous ; pappus of 2 awl-shaped awns. 



Frequent along streams, borders of thickets, etc., in moist rich 

 soil, July-Sept This is probably the most common and widely 

 distributed of the 16 species of wild sunflowers recorded from the 

 State. All are weeds in that they grow uncultivated in waste 

 places, yet no one of them is a weed of the first or even the second 

 class. All agree in having conspicuous yellow rays which are 

 neutral, that is, without pistils or stamens, in having the receptacle 

 chaffy, the chaff arising from beneath the tubular disk-flowers, and 

 in the pappus being represented by only 2 or 4 short scales or awns. 

 The ray-flowers exist only for the purpose of attracting insects to 

 the less showy fertile flowers of the disk, thus indicating a high 

 type of division of labor in plant life. The leaves vary much in 

 size, shape, position on the stem, smoothness, length of stalk, etc., 

 and by these differences the species are mainly separated. In a 

 few the disk-flowers are brown or purple and the receptacle flat, 

 but in most kinds the disk is yellow and the receptacle convex. 

 The generic name, Helianthus, means sunflower and probably refers 

 to the popular belief that these flowers turn or change position on 

 the stalk so as to face the sun most of the time. This belief is set 

 forth by Thompson in the lines : 



"The lofty follower of the sun, 

 Sad when he sets, shuts up her yellow leaves, 

 Drooping all night, and, when he warm returns, 

 Points her enamoured bosom to his ray." 



And Moore, describing its faithful constancy, says: 



