Flora of Denver. 23 



181. Antennaria dioica G^RTX. (EVERLASTING-FLOWER.) 

 Forming mats, bracts of the involucre papery, white or pink, 

 flowering stems low. North Denver and Berkeley. Spring. 



182. Antennaria plantaginifolia HOOK. Similar to the 

 above, flowering stems much taller and heads smaller. Clear 

 Creek. Not common. Summer. 



183. Gnaphalium Sprengelii HOOK. & ARN. Stems leafy, 

 leaves sessile covered with loose white wool. Heads clustered 

 at top of stems, bracts of the involucre yellow becoming brown- 

 ish. North Denver. Fall. 



184. Gnaphalium strictum GRAY. Wool of stem and 

 leaves close, flowers clustered along the stem at the axils, bracts 

 of involucre brownish. Along the ditches. Summer and fall. 



185. Iva xanthiifolia NUTT. A tall coarse weed with op- 

 posite broad coarsely serrate leaves, heads panicled at top of 

 stem often becoming a dark brown. Summer and fall. 



186. Iva axillaris PURSH. About a foot high, drooping 

 heads solitary in the axils of the leaves. North Denver. 

 Summer. 



187. Ambrosia trifida L. (RAGWEED.) Tall, opposite 

 leaves deeply three or at base five-lobed, fruit with spiny pro- 

 jections. Common. Fall. 



188. Ambrosia artemisiaefolia L. Branching diffusely 

 above, leaves dissected into narrow divisions, fruit clustered, 

 short-spined. Common. Fall. 



189. Ambrosia psilostachya DC. This is found with the 

 preceding but can easily be distinguished. At the lower part 

 f stem, divisions of leaves broader; fruit solitary and without 

 spines. 



190. Franseria Hookeriana NUTT. Branching diffusely, 

 leaves bipinnatifid broad, white hairy; spines of the fruit re- 

 curved, awl shaped. North Denver. Fall. 



