186 GENUS CHRYSOTHAMNUS. 



distributed as C. glaucus Nelson. These specimens have the very acute bracts of stenolepis, but the leaves are 

 mostly flat, 3 mm. wide, and the shrubs were not reduced in size. Their combination of characters indicates an 

 intermediate stage. C. stenolepis is worthy of detailed studies in the field, where it may be found that, at least 

 as far as the type form is concerned, it is a wide-leaved and narrow-bracted variation from subspecies pumiitw. 



30. C. STENOPHYLLUS Greene, Erythea 3:94, 1895. — C. viscidiflorus stenophyllus. 



31. C. TORT1FOLI0S Greene, Fl. Fran. 368, 1897. — C. viscidiflorus and its subspecies, as noted under No. 9. 



32. C. VISCIDIFLORUS Nuttall, Trans. Am. Phil. Soc. II, 7:324, 1840. — C. viscidiflorus typicus. 



33. C. VISCIDIFLORUS var. lanceolatus Greene, Erythea 3 : 95, 1895. — C. viscidiflorus subspecies laruxolatus. 



34. C. VISCIDIFLORUS var. latifolius Greene, 1. c. 96. — C. viscidiflorus subspecies latifolius. 



35. C. viscidiflorus var. serrulatus Greene, 1. c. — The same as No. 42 of this list. 



36. C. viscidiflorus var. tortifolius Greene, 1. c. — Various subspecies of C. viscidiflorus are included under 

 this name. (See No. 9.) 



37. C. viscidiflorus typicus, but with comparatively short and very green leaves. This form grows on 

 sandy flats near Chambers Station, northeastern Arizona {Hall 11151, 11152, UC). The plants are 4 to 7 dm. 

 high, woody to the top, the twigs erect and fastigiately crowded; leaves 1 to 2 mm. wide, 1 to 2 cm. long, gla- 

 brous and green; involucre 6 mm. high; bracts in distinct vertical rows, acute, greenish but without definite spot. 

 Apparently distinct from typical viscidiflorus, but the differences are superficial. The plants show evidence of 

 top-browsing, which may account for their fastigiate habit, and the reduction in leaf may be the result of unfa- 

 vorable sou conditions. 



38. C. viscidiflorus typicus, but with leaves only 0.5 to 1 mm. wide. This variation is of rare occurrence 

 and may be more than a response to ecologic conditions. The extreme form is represented by a collection from 

 the Snake River sands north of Hagerman, Idaho, September 18, 1919, Hall (UC). A complete series of inter- 

 grading forms is not at hand but as intermediates may be cited: 8 km. southwest of Redmond, Oregon, Septem- 

 ber 29, 1918, Whited (UC), and Grizzly Butte Spur, eastern Oregon, Leiberg 855 (UC). 



39. Crinitaria viscidiflora Hooker, Fl. Bor. Am. 2:24, 1834. — ^The type of the species, therefore C. vis- 

 cidiflorus typicus. 



40. Linosyris lanced lata Torrey and Gray, Fl. N. Am. 2: 233, 1842. — C. viscidiflorus lanceolatus. 



41. L. PUMILA Gray, PI. Wright. 2:80, 1853. — C. viscidiflorus pumilus. 



42. L. serrulata Torrey, Stansbury Rep. ed. 1:389, 1S51. — The form of this as originally described from 

 specimens from the Valley of Salt Lake differs from C. viscidiflorus typicus only in the scabrid or stiffly short- 

 ciliate leaf-margins. There are numerous intermediate forms in which the margins vary from smooth to 

 strongly scabrid, so that it becomes impossible to draw a line between typica and serrulata. Moreover, every 

 glabrous subspecies includes forms with scabrid-margined leaves, as weU as others in which the margins are 

 smooth. Thus, the recognition of this as a subspecific character would necessitate the erection of at least 5 

 new subspecies. A good example of serrulata is Leiberg 894, from eastern Oregon. One of the intermediate 

 forms is Butler 1731, from Siskiyou County, California, in which collection the leaves are mostly scabrid on the 

 margins, but only minutely so and for only a portion of the distance. 



43. L. VISCIDIFLORA Torrey and Gray, Fl. N. Am. 2: 234, 1842. — C. viscidiflorus. 



44. L. VISCIDIFLORA Var. latifolia Eaton, Bot. King's Expl. 157, 1871. — C. viscidiflorus latifolius. 



45. L. VISCIDIFLORA var. puberula Eaton, 1. c, 158, 1871. — C. viscidiflorus puberulus. 



46. L. VISCIDIFLORA var. serrulata Torrey in Stansbury Rep., ed. 2:389, 1853. — A reduction of Linosyris 

 serrulata, which see in this list. The dates here given for the two editions of Stansbury's Report are as indi- 

 cated by CoviUe (BuU. Torr. Club 23:137, 1896). 



RELATIONSHIPS. 



The only species to which C. viscidiflorus is closely related is C. greenei, but there can 

 be no doubt as to the close affinity between these two. The reasons for considering 

 them as distinct are stated under the latter species. C. vaseyi has been frequently com- 

 pared with varieties of viscidiflorus, but its achenial characters indicate that the connec- 

 tion is not very close, as has been already pointed out (p. 180). There is no evidence which 

 permits a linking of viscidiflorus with any species of the other sections of Chrysothamnus. 



Evolutionary forces have been operating upon C. viscidiflorus for a long period of time, 

 as indicated by the large number of variations that have been produced. However, 

 judging from the numerous intergrades that are constantly being found, it seems just as 

 evident that the resulting variations have been held together in one rather close major 

 species, perhaps through interbreeding where their ranges meet or overlap. Absolute 

 intergrading is, of course, almost impossible to demonstrate without a close genetic 



