THE FLORA OF SCOTT AND MUSCATINE COl NTIES. 281 



Cnicus Hillii, Canby. (iarden and Forest 4:101, 1891. 



Observations made since the publication of this species in 1891, 

 and accurate drawings, furnish material for a more complete descrip- 

 tion and understanding of this thistle, which well maintains its claim 

 to specific rank. 



Plant perennial, 1 — 2 feet high, leafy, simple or branched, villous 

 pubescent or somewhat woolly. Root 8 — 15 inches long, simple or 

 fasicled (1 — 4), generally perpendicular, the parts fusiform or the mid- 

 dle portion more or less enlarged and hollow or coarsely cellular, 

 slender above. Leaves sinuate lobed to pinnatifid, or the lower undu- 

 late, the lobes rather broad and rounded, green both sides, acute or 

 the lower obtuse, dentate, spinulose or with a few short prickles; the 

 upper oblong to oblong-lanceolate, sessile and clasping; the lower 

 oblanceolate to spatulate-oblong, narrowed at the base, or the lowest 

 petioled and 6 — 8 inches long. Vernal and autumnal leaves rosulate, 

 oblanceolate-oblong, entire or slightly undulate, with short and weak 

 marginal prickles, or sometimes with stouter yellowish prickles. 

 Heads 1 — 3 (1 — 5), frequently single, 2 — 3 inches broad, 2 — 2)^ 

 inches high. Outer involucral bracts ovate-lanceolate, tipped with a 

 short bristle or prickle, with a dark and prominent glutinous line 

 along the back, inner, narrowly lanceolate, long acuminate. Flowers 

 purple, pappus slender pointed or sometimes slightly spatulate. 



Fields and open woods. June 20 — Aug. 1. 



The main distinctions between this and the pasture thistle [Cnicus 

 pumilus, Torr.), its nearest ally, and with which it was at first con- 

 founded, are the duration and form of the root, that of the pasture 

 thistle being biennial and branched, while in this it is perennial, sim- 

 ple, with a few rootlets, mainly on the lower half; its less spinescent 

 and less deeply lobed or divided leaves; the bracts of the involucre 

 more glutinous; their weaker tips which are scarcely prickly except 

 in the lowermost; the longer and more slender pappus; the earlier 

 flowering season, the first half of summer, while that of C. pumilus is 

 the latter half. The leaves of the pasture thistle cover the stem well 

 up to the head to which they may form a kind of involucre, while 

 those of C. Hillii are few and small near the head, or the stem may 



[Proc. D. A. S., Vol. VIII.] 36 [Aug. 2.1, 1900.J 



