No. 586] 



ANNUAL SUNFLOWERS 



(ii:; 



This is a good species in the ordinary sense; in Colo- 

 rado it is often found abundantly in the canons of the 

 foothills, growing without admixture of other species. 

 Lower down, it frequently oeeurs with lenticularis. 



The variety patens (Lehm.) Rydb. is said to differ by 

 having the heads larger, long-peduncled, the peduncles 

 fleshy toward the top; leaves large, long-petioled. Nut- 

 tall described his original petiolaris as having the pedun- 

 cles "of great length," and the petioles "of an ex- 

 traordinary length," though the leaves were "rather 

 small." Probably patens is not far from the original 

 petiolaris. Gray considered patens a synonym. Ac- 

 cording to Rydberg, the leaves of patens are broadly 

 ovate or subcordate, much in the style of lenticularis, 

 while the bracts are those of petiolaris, thus reversing 

 the condition of a rid us. It is possible that arirlus and 

 patens are both remote results of the lenticularis Xpetio- 

 laris cross, but in the vieinitv of Boulder, when aridus is 

 common, I have not found patens. 



5. H. emus (Britton) Wooton and Standley. A 

 species of New Mexico, Chihuahua, and adjacent regions, 

 close to petiolaris, but with abundant white pubescence 

 on leaves and stems. The involucral bracts are of the 

 petiolaris type. This is to petiolaris much as B. 

 arqophulhis is to 1< uticularis, but the pubescence is long 

 and spreading, not subappressed and silky. 



6. H. argophyllus Torrey and Gray. Discovered by 

 Drummond in dry soil in Texas. This has the form and 

 leaves of lenticularis, but is very remarkable for the long 

 subappressed silky white hairs, totally different from 

 those of any other Helianthus known to me. Gray re- 

 marks that it " degenerates in cultivation apparently into 

 71. auuuus," which merely means that it suffers from 

 vicinism. Old cultivated stocks, kept pure, are quite con- 

 stant. A remarkable feature of 77. argophyllus is the 

 extremely slow growth, at least until near flowering time. 

 This peculiarity is dominant in a cross with H. annuus X 

 lenticularis. 



