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THE AMERICAN NATURALIST [Vol. XLIX 



(6) Aspect of lenticularis; more or less robust, rays rather short and 



(i) Kays comparatively short and broad (about 22 mm. long 



and 10 broad on a small head), the middle third 



(ii) Rays normal. ' ? 



lateral. Disc small (22 mm. diam.), rather paler 

 than usual, the corolla lobes showing less red. 

 Rays 14, about 31 mm. long and 11.5 broad. 



rather feebly dentate. Disc 20-23 mm. diameter. 



short rays, about 17 mm. long and 7 broad. 

 (7) Typical h ntunhni*. uirl, 1 .road-based strongly den- 

 It would of course be possible to maintain that E. 

 aridus was originally a distinct or isolated species, which 

 has now lost its purity by crossing with lenticularis. We 

 can at least say this, that if annuus, lenticularis and 

 aridus, in their pure forms, inhabited three different 

 islands, few would hesitate to regard them as perfectly 

 "good species." Also, if they grow mixed for any 

 length of time, they are sure to suffer from " vicinism " 

 to such an extent as to lose their supposed original dis- 

 tinctness. At present, however, we have no assurance 

 that E. aridus has ever constituted a distinct species, in 

 the sense of occupying any considerable area in its pure 

 form. On the other hand, it is manifestly not a 1 1 fluctuat- 

 ing variation," due to mere environmental conditions. 



4. H. petiolaris Nuttall. Described by Nuttall in 

 1821, from "the sandy shores of the Arkansa," and 

 recommended as "an ornamental annual of easy cul- 

 ture." It extends from British America to the State of 

 Chihuahua. It differs from H. lenticularis by (a) 

 smaller stature, (b) leaves differently shaped, lanceolate 

 or broad-lanceolate, not dentate, more or less shiny above, 

 those of lenticularis being quite dull, (c) bracts of invo- 

 lucre lanceolate, with margin very short-ciliate. Stem 

 rough, with a little purplish color; basal third of rays 

 deeper orange than the rest. 



