496 



WEED FLORA OF IOWA 

 Chicory (Cichorium intybus L.) 



Aehenes oblong, ribbed, 5-<angled, spotted, grayish or straw- 

 colored, with darker spots, one-twelfth to one-eighth in. in length 

 apex with the base of the pappus scales extending beyond the scar ; 



Fig. 374. Chicory (.Cichorium intybus). A, B, two views of seeds; C, seeds, 



natural size. 

 (After Hillman, Bull. Mich. Agr. Exp. Sta.) 



minutely, transversely roughened ; base of seed lighter in color, with 

 small depressed scar ; aehenes from the inner part of the flower more 

 slender and straight than from outer part. Found with various 

 commercial seeds. 



Corn-flower (Centaurea cyanus L.). 



Achene oblong or obovoid, compressed, one-sixth to one-fifth in. 

 long; smooth, shining; with inconspicuous veins or nerves; lower 

 part of achene oblique ; ivory-white ; the elliptical or somewhat cir- 

 cular scar at base with whitish rimmed border, depressed, made up 

 of soft tissue; pappus of several series of scaly bristles; brownish 

 in color. The achenial trichomes, according to Mr. Fracker, are 

 long and simple. 



Barnaby's Thistle (Centaurea solstitialis L.). 



Involucre ovoid, 1.5 cm. in diameter, with stout straw-colored 

 spines, widely spreading ; achene cream or pale brown after matted ; 

 length 2 mm., scar of attachment in a notch above rounded base; 

 apex truncate, bearing tubercle in the center. 



