No. 586] 



ANNUAL SUNFLOWERS 



619 



than other sunflowers in its early stages. The var. 

 chrysanthemoides was found by us to cross freely with 

 the annuus X lenticular is varieties, producing a series of 

 semi-doubles. The double and semi-double forms ex- 

 tracted from this cross and from crosses with Sutton's 

 various double forms need not be described here, but in 

 order to illustrate the double type, I give a figure of a 

 full double with chestnut color, the red being derived 

 from the variety coronatus (Fig. 1). 



Modifications of the Eays 

 Number.— Halsted (Eept. Bot. Dept. N. J. Agric. Exp. 

 Sta. for 1911, pp. 335-337) has given elaborate data from 

 the branched form of the cultivated H. annuus, showing 

 that the terminal heads have most rays, and when there 

 are many lateral branches, the rays on these are com- 

 paratively few. Nevertheless, there are inherited differ- 

 ences in the number of rays, not depending on conditions 

 of nutrition. I observed a striking case by the roadside 

 in Boulder, where three wild Jciiticuhiris plants, growing 

 close together, differed thus : 



(a) Eays normal, at right angles to axis ; number of rays 

 in well-formed heads, 21, 21, 21, 21, 20, 21, 21. 



(b) Eays normal, elevated, their plane oblique in rela- 

 tion to the axis of head ; rays in well-formed heads, 

 14, 13, 14, 14, 14, 11, 15. 



(c) Eays set obliquely, but less so than in b ; rays in well- 

 formed heads, 18, 18, 18, 19. In this plant many of 

 the rays were modified by quilling and splitting, some 

 being completely quilled, i. e., hollow and tubular. 

 The normal rays were very obtuse, and distinctly 

 emarginate at end. Some showed a little red color on 

 apical part of middle third beneath. 



Length. — The length also differs, the differences due 

 sometimes to race, sometimes to illumination or nutri- 

 tion. In our cultures mutational forms have arisen with 

 unusually short rays, thus: 



(a) Var. vinosus with disc 55 mm. broad, rays only 35 

 mm. long ; disc unusually convex. 



