180 GENUS CHRYSOTHAMNUS. 



Plateau, Utah, Ward 620 (US); Chama, northern New Mexico, September 5, 1899, 

 Baker 652 (NY, US, type collection of C. bakeri Greene, minor variation 2) ; near Dulce, 

 Rio Arriba County, New Mexico, Standley 8134 (US). 



MINOR VARIATIONS AND SYNONYMS. 



1. BiGELOViA VASETi Gray, Proc. Am. Acad. 12:58, 1(S76. — C. vaseyi. 



2. Chrtsothamnus bakeri Greene, Pittonia 4:152, 1900. — Described from plants collected by Baker near 

 Chama, New Mexico, and compared with C. greenei, from which, however, it differs in the obtuse bracts, gla- 

 brous achenes, and other characters. On the other hand, specimens of the type collection are exactly like the 

 usual form of C. vaseyi, which was probably overlooked when bakeri was diagnosed. 



RELATIONSHIPS. 



This species is well separated phylogenetically from all of the others, as is especially 

 indicated by the character of its achenes and of its style-branches. Greene has already 

 pointed out (Erythea 3:96, 1895) that the former are longitudinally 10-striate. They 

 are therefore unlike any others in the genus except in the Pulchelli and in the recently 

 described C. gramineus. The style-branches are of a peculiar shape. Although plainly 

 flattened, the short, thick, somewhat rounded appendage gives them the appearance of 

 being almost club-shaped. This appendage is shorter in proportion to the stigmatic 

 part than in any other Chrysothamnus, except in occasional specimens of C. greenei. 

 It is to this species that vaseyi is probably most closely related, as is indicated by the 

 appearance and by the general assemblage of characters as well as by the style-branches. 

 However, even this alliance can not be very close, because of the very short, angular 

 achenes and abruptly acute bracts of greenei. There is a close similarity in appearance 

 between this species and certain subspecies of C. viscidiflorus, such as pumilus, but 

 this is only superficial, as is indicated by the important differences in the achenes and 

 style-branches already referred to. A comparison with Petradoria pumila has been sug- 

 gested, and it is possible that there is some connection between these two species and 

 also between them and the true Bigelovias, that is, Chondrophora of some botanists. 

 Petradoria, however, is an herb with radiate heads, subulate style-appendages, and 

 flattish 5-nerved achenes, while the true Bigelovias, also herbs, differ from C. vaseyi 

 in a number of characters, as pointed out in the introduction (see p. 157). Chrysothamnus 

 vaseyi is fairly consistent and non-variable, as is indicated by the fact that no segregate 

 species or varieties have been described, with the single exception of C. bakeri Greene, 

 and that apparently through an oversight, as already mentioned. 



ECOLOGY AND USES. 



Chrysothamnus vaseyi occurs in grassy mountain parks at altitudes of 6,000 to 8,500 

 feet, for the most part forming societies in the mixed prairie. In southwestern Colorado 

 and adjacent Utah, it is associated with the sagebrush. It is a low undershrub, blooming 

 during August and September. 



It is unlikely that any considerable use can be made of C. vaseyi. The plants are 

 doubtless browsed by sheep, but they are quite small and apparently nowhere abundant. 



5. CHRYSOTHAMNUS VISCIDIFLORUS (Hooker) Nuttall, Trans. Am. PhU. Soc. II, 

 7 : 324, 1840. Plates 26 and 27. 



Shrub of exceedingly diverse habit, 1 to 12 or even to 24 dm. high, commonly much 

 branched from the simple base and forming a round-topped bushy plant; bark of the 

 main stems brown, fibrous; twigs brittle, erect, leafy, glabrous or minutely puberulent, 

 with a pale green or white bark, striate; leaves narrowly linear to oblong or lanceolate, 

 often considerably twisted, acute or obtuse, 1 to 6 cm. long, 1 to 10 mm. wide, 1- to 

 5-nerved, rather rigid, glabrous or puberulent, viscidulous, the margins commonly sca- 

 brous; heads in terminal rounded or flat-topped cymes; involucre 5 to 8 mm. high; bracts 



