84 



make any distinction in color between the two types. Several 

 of the larger expanded heads from robust plants of the glabrous 

 t>'pe, growing in a cornfield late in the season, were found to 

 measure from \]/2 to \yi inches across — or even more in some 

 cases. No glandular t^^pe heads of similar robust plants being 

 available, those of fresh late roadside growth were measured 

 and were found to be slightly less than i ^ inches across. Closed 

 involucres of the glabrous t>^pe with petals dropped and tapering 

 to a blunt point from a rounded "knobby" base were found to 

 be about % inch high with a width at the rounded "knobby" 

 base of about ^ inch. Enough such heads were fitted to a 

 scale drawn in a notebook to indicate that this was a fairly 

 close average for maximum size mature heads. Unopened buds 

 varied with age and were blunt. Heads from the glandular 

 t}'pe approximated the same average measurements. The in- 

 volucre of both t>^pes is rather light green even in pressed ma- 

 terial, unless badly cured in pressing. 



Heads of the glandular t^^pe appear always to have glandular 

 hairs plentifully present over the involucre, and glandular hairs, 

 at times sparingly or abundantly, have been noted to extend 

 along the branches of the inflorescence as far as 6 to 7 inches 

 below the tops of the heads. The absence of glandular hairs on 

 the branches of the inflorescence in many plants of late growth 

 of the glandular t\^pe has already been noted. Plants of the 

 glabrous type appear to be quite destitute of glandular hairs 

 but in all material examined sticky dots, usually roundish in 

 outline, are present in varying abundance along the edge of the 

 involucral bracts of the heads (even in bud) as well as elsewhere 

 on the surface. These "gummy" or sticky dots have been 

 noted to cause heads of the glabrous type to stick slightly to the 

 paper in pressing. They have also been noted on material of 

 the glandular type but more rarely and it is possible that they 

 represent excrescences caused through puncture by sucking- 

 insects. 



Achenes of the glabrous type examined were brown in color, 

 oblong, slightly tapering, compressed and with 12 heavy longi- 

 tudinal, rugose ribs. Those of the glandular type examined 

 appear to be quite similar. 



It is hoped that the above observations may be found helpful 

 in a study of this plant. Material representing all collections 



