Wild Flowers East of the. Rockies 363 



ROSIN-WEED; COMPASS PLANT (Silphium lacin- 

 iatum) is a large, showy-flowered plant found on the 

 western prairies. It has a stout, rough, bristly stem 

 that attains heights of from three to ten feet. The 

 stem grows from a perennial root; it exudes copious, 

 resinous juices. The large leaves are pinnately divid- 

 ed, each division being linear and cut-lobed; they are 

 on long, broad petioles that spread into clasping 

 bases. 



The flower heads are very large, measuring from 

 two to four inches across. They are sessile or ex- 

 ceedingly short-stemmed, seated along the upper 

 portion of the stout stem. Their arrangement is 

 quite similar to that of Chicory, the well known and 

 common flower in the East. The bracts of the in- 

 volucre are long and taper into spreading points, that 

 spread nearly as wide as the ray florets; the central, 

 tubular florets form a large, flat orange ."button" and 

 are surrounded by bright yellow, notched rays. The 

 lower and root leaves are very large, ranging from 

 one to three feet in length. They are disposed to 

 present their edges north and south. Compass plant 

 is found on prairies from Mich, to North Dakota and 

 southwards; it blooms from July until September. 



PRAIRIE DOCK (Silphium terbinthinaceum pinnat- 

 ifidium), in spite of its cumbersome Latin name, is 

 rather an attractive plant that also grows on prairies 

 and the edges of copses. The smooth, slender str^p 

 ascends 3 to 10 feet high and bears a loose panicle of 

 large, yellow-rayed flower heads. The leaves mostly 

 come from the root and lower part of the stem- they 

 are slender-petioled and deeply pinnatifid. Found 

 from O, to Minn, and southwards 



