C. VISCIDIFLORUS. 189 



The subspecies elegans has every appearance of an ecologic derivative of lanceolatus, 

 from which it is best distinguished by its narrower leaves. The presence of the thickened 

 spot on the bracts is not always easily made out, since it varies much in the degree of 

 development. It recurs elsewhere in the species only in linifolius, but it does not indicate 

 a close genetic connection between these two subspecies, as is shown by their divergence 

 in other characters. On the contrary, elegans represents a closed circle in that it has 

 given rise to no other variations of importance. The specimens indicated as the types 

 at the Greene Herbarium are mounted on two sheets. Unfortunately, one of these 

 (26610) bears also a piece of C. vaseyi, positively identified by its essentially glabrous, 

 elongated, 10-ribbed achenes and also by the non-tortuous leaves. This specimen is 

 the lower middle one of the three on the sheet. The other two have achenes and foliage 

 as described for elegans and, together with the other sheet, all of the specimens of which 

 are genuine, may be taken as the types. 



As is so often the case, the first form described under the species is not the most 

 primitive. Therefore, subspecies typicus is represented on one of the diverging lines 

 of the diagram. The type specimen is not now accessible to us, but it is fairly well 

 defined in the original description, which in full is as follows : 



C. viscidiflora ; glaberrima, foliis lineari-laneeolatis rigidis integerrimis acutissimis uninerviis basi angustatis, 

 floribus fastigiato-corymbosis, pedunculis foliolosis, involucri glutinosi cylindrici 5-flori foliolis imbricatis 

 oblongis exterioribus minoribus (Hooker, Fl. Bor. Am. 2:24, 1834.). 



Hooker then refers to the plant as a common shrub, 6 to 12 dm. high, and in comparing 

 it with Chrysocoma graveolens, he states that it differs in the leaves being only single- 

 nerved and the branches quite glabrous, not in the least pulverulently tomentose. This 

 identifies the type very satisfactorily with a common form of the Northwest, except that 

 in plants which correspond in every other way the leaves are usually but not always 

 3-nerved. This is not taken as a matter of importance, for the character is extremely 

 variable and the two additional nerves are often so faint as to be easily overlooked. 

 In order to avoid the setting up of a new subspecies, it is necessary also to include in 

 typicus a rare form with narrowly linear instead of linear-lanceolate leaves, as indicated 

 by minor variation 38. 



Close to the type form, but differing in its wider leaves with a larger number of veins, 

 is subspecies latif alius. The center of its distribution is northeastern Nevada, whence 

 comes the extreme form with very wide elliptic leaves. The smooth green foliage and 

 general appearance suggest linifolius, but the bracts are much thinner and the plants 

 probably are not alkali-tolerant. It is more likely a direct offshoot from typicus. 



The robust habit, large, thick leaves, and thickened spot on the bracts render linifolius 

 the most striking of all the subspecies when it occurs in its extreme development. But 

 in all of these characters, which are doubtless the result of its strongly alkaline habitat, 

 it intergrades into typicus and latifolius. This may be noted in the vicinity of Point 

 of Rocks, Wyoming. Here the plants growing on alkaline soil have all of the characters 

 of linifolius, while by selecting areas where the alkali is less abundant, such as those 

 lying to the west, all gradations in the characters may be noted until the plants are in 

 no way distinguishable from typicus. 



ECOLOGY. 

 The low forms of Chrysothamnus viscidiflorus constitute typical societies in the south- 

 western portions of the mixed prairie and throughout the sagebrush association of the 

 Great Basin, while the taller ones, such as typicus, are rather to be regarded as consocia- 

 tions of the sagebrush. The former are also abundant in cedar savannah. Pumilus, 

 lanceolatus, and serrulatus are the common subspecies of the mixed prairie, and often 

 become controlling as a result of overgrazing. In this respect they closely resemble 



