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 svbspecies of Artemisia tridentata. 



Height. 



No. of 

 bracts. 



No. of 



flowers 



per bead. 



Length of 

 corolla. 



Subspecies typica: 



Medicine Bow, Wyo . . . 



Hosier, Wyo.' 



West of Bosler, Wyo'. . 



Do.' 



Clear Creek, Colo 



Tintic, Utah 



Snowville, Utah 



Albion, Idaho 



Eastern Oregon 



Weber Cafion, Utah. . . 

 Pleasant Valley, Oreg. . 

 Siskiyou County, Calif. 

 Shasta Valley, Calif.... 



Mint Canon, Calif 



Kern County, Calif. . . . 

 Nighthawk, Wash 



Average . 



Subspecies parishi: 



Rosamond, Calif 



Do 



Do 



Newhall, Calif.' 



Ventura County, CaUf. 

 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 



CI 

 CI 

 CI 

 CI 



29790 UC 



172630 UC 



CI 



CI 



29789 UC 



CI 



CI 



166167 UC 



CI 



CI 



34171 UC 



175960 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 

 3.0 

 3.1 

 3.2 

 3.3 

 3.2 

 3.5 



3 1 

 3.5 

 3.4 

 3.0 

 3.3 

 3.5 



3 5 

 3 

 3.2 

 3.8 

 3.0 

 3.0 

 3 



2.8 

 3.4 

 3.7 

 3.3 

 3.2 

 3.4 

 3.3 

 2.7 

 3.0 

 3.0 



mm. 

 2.5 

 2.2 

 2.2 



2.2 

 2.4 

 2.1 

 2.7 

 2.5 

 2.1 



3 

 2.6 

 2.4 

 2 6 

 2.3 

 2 5 

 2 1 



2.0 

 2.2 

 2.4 

 2.0 

 1.8 

 2.2 

 1.9 

 1.8 

 2.4 

 1.7 



7 10 

 7 9 



7 8 



12 12 



8 10 



9 11 



13 14 



10 14 



8 10 



9 10 



11 12 

 10 11 



9 

 16 17 



8 9 

 15 



4 4 



4 4 



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 



16 18 



15 18 

 13 11 



16 19 

 9 11 



12 13 

 9 10 



13 



5 5 

 5 6 



4 4 

 4 4 

 4 5 



Average . 



8 10 



6 7 



8 7 



9 9 



10 11 



11 12 



7 8 

 7 8 



12 12 

 7 8 



3 3 



5 6 



3 3 



4 3 



3 5 



4 4 

 4 4 



3 3 



4 4 

 3 3 



mm. 

 2.0 

 2.2 

 2.7 

 2.6 

 2.0 

 2.4 

 2.4 

 2.4 

 2.5 

 2.0 

 2.0 

 Young 

 2.6 

 2.6 

 2.0 

 2.0 



2.2 



2 

 2.3 

 young 

 2.4 

 2 6 

 2 

 2 



2 3 



2.1 



2.6 



3.0 



2.4 

 Young 



2.5 



2.5 

 Young 



1.9 

 Young 



2.4 



