224 IOWA ACADEMY OF SCIENCES. 



there is a difference with reference to the character of the 

 bristles. In some species the outer flowers are merely bar- 

 bellate as in C. muticus and C. discolor. The branches of 

 the pappus are usually clavate. The pappus is so arranged 

 that it forms a neat contrivance for the wind to carry the 

 fruit for a considerable distance from where it was pro- 

 duced. One often can see hundreds of these little downy 

 affairs floating in the air. For this reason so many of the 

 plants make their appearance in clearings, as in pastures 

 and burnt timber. The Cnicm lanceolatns frequently occurs 

 in such abundance in pastures as to seriously injure the 

 value of the same for pasture purposes. One sees the 

 same thing in a forest burned over in the course of a year 

 or so in this state The Cniciis lanceolatus comes up in 

 abundance. In the Rocky mountain country the Ciiicns 

 dnuNmondii becomes abundant; in the course of a few 

 years the open woods become covered with these plants, 

 and not inappropriately are sometimes called lire weeds. 



CNICUS. 



Cnicus, L. Gen. 6 Ed. 1764. Tourn Inst. 447. t 255. 



Linn. Sp. PI. 1763. 2 Ed. 



Willd. Sp. ;i: 1662. 



Bentham & Hooker Gen. PI. 2: 468, 1236. 1873. 



Cirsium, D.C. Fl. Fr. 4: 110. 1805. 3 Ed. 



Prodr. 6: 634. 1837. 



Hoffmann in Engler and Prantl. Die Nat. 



Pflanzenfamilien. Theil IV. 5 Abt. 322. 1893. 



Carduus, L. Sp. PI. 820. 1753. 



— Greene. Proc. Acad. Nat. Sci. !892: 



Britton and Brown Illustr. Fl. N. St. 3: 484 in 



part. 1898. 



Erect branching or simple caulescent or a few acaul- 

 escent herbs, with alternate sessile, or decurrent, decum- 

 bent sinuate dentate or pinnatifid spiny leaves, involucre 

 ovoid or globose, bracts of two series, the outer armed 

 with a prickle or without, with a glutinous ridge or none, 

 the inner long acuminate, frequently with a scarious 

 appendage. Large many-flowered, solitary or clustered 



