146 



GENUS ARTEMISIA. 



northerly part of the area covered by A. tridentata. In his original description Nuttall 

 included with this some specimens of what is now known as nova, another subspecies 

 also adapted to a severe environment but along somewhat different lines. 



The subspecies rothrocki is of uncertain derivation. Its sporadic occurrence at widely 

 separated localities indicates that it is of polygenetic origin. In this case the parent 

 quite certainly is typica, since none of the other forms has a range sufficiently extensive 

 to cover all of the stations for rothrocki. The attempt of others to specifically recognize 

 forms here included under this subspecies would seem to indicate that it is not homo- 

 geneous, but when identical forms are found in areas so widely separated as California 

 and Colorado the distinctions break down entirely. The proposals referred to are 

 spiciformis and vaseyana, both of which are fully discussed under the heading of minor 

 variations. The identical forms are perhaps best considered as parallel variations from 

 the parent typica stock. The large number of flowers in the head may indicate rothrocki 



Table 14. — Variation in the subspecies of Artemisia tridentata. 



No. of 

 flowers 

 per head. 



Length of 

 corolla. 



Subspecies lypica: 



Medicine Bow, Wyo . . . 



Hosier, Wyo.' 



West of Bosler, Wyo> . . 



Do.' 



Clear Creek, Colo 



Tintic, Utah 



Snowville, Utah 



Albion, Idaho 



Eastern Oregon 



Weber Canon, Utah. . . 

 Pleasant Valley, Greg. . 

 Siskiyou County, Calif. 

 Shasta Valley, Calif.... 



Mint Cafion, Calif 



Kern County, Calif. . . . 

 Nighthawk, Wash 



Average. 



Subspecies pariehi: 



Rosamond, CaUf 



Do 



Do 



Newhall, Calif.' 



Ventura County, Calif. 

 Mojave Desert, Calif. . . 

 Carson Sink, Nev 



Average . 



Subspecies nova: 



South of Laramie, Wyo 



Albany County, Wyo 



Laramie, Wyo 



Laramie Hills, Wyo 



San Francisco Mountains, Ariz. 



Buckskin Mountains, Ariz 



Panguitch Lake, Utah 



Mount Irish, Nev 



Strevell-Albion, Idaho 



Inyo Range, Calif 



Average . 



CI 

 CI 

 CI 

 CI 

 29790 UC 



172630 UC 

 CI 

 CI 

 29789 UC 

 CI 

 CI 



166157 UC 



CI 



CI 



34171 UC 



176960 UC 



CI 



75851 UC 

 74055 UC 

 54010 UC 



205802 UC 

 Gr 



128181 UC 



CI 

 69457 UC 

 146504 UC 

 91181 UC 

 135368 UC 

 159117 UC 

 159393 UC 

 135367 UC 

 CI 

 202351 UC 



mm. 

 3.0 

 3.0 

 3.2 



2.1 

 2.7 

 2.5 

 2.1 



9 11 

 13 14 

 10 14 



10 11 

 9 

 16 17 



4 4 



4 4 



4 5 



4 4 



4 5 



4 5 



3 3 



4 4 



3 4 5 



4 5 



3 4 



4 4 



3 4 



4 6 5 



13 11 

 16 19 



9 11 

 12 13 



9 10 



13 



8 10 

 6 7 



8 7 



9 9 



2.0 

 2.2 

 2.7 

 2.5 

 2.0 

 2.4 

 2.4 

 2.4 

 2.5 

 2.0 

 2.0 

 Young 

 2.5 

 2.6 

 2.0 

 2.0 



2.2 



2 

 2 3 

 young 

 2.4 

 2 6 

 2.0 

 2.0 



2.3 



2.1 



2.6 



3.0 



2.4 

 Young 



2.5 



2.5 

 Young 



1.9 

 Young 



2.4 



