A. TRIDENTATA. 



143 



character. Its inclusion would introduce a new series of combinations, with the addi- 

 tional characters of pubescence of achene, drooping of the inflorescence, and width of 

 leaf. 



Some of the tabulated forms exhibit additional divergent features. Since these may 

 be expected in each of the other forms, the total number of possible combinations 

 becomes so great that no practicable system of nomenclature can provide for them. 

 Such features include drooping inflorescences, reduced number of flowers, dark foliage 

 associated with low stature and narrow inflorescence, density of pubescence, color and 

 looseness of pubescence (see subspecies bolanderi), and relative lengths of inner and 

 outer bracts of the involucre. 



Table 13. — Character combinations found in Artemisia tridentata. 



The most anomalous subspecies is parishi, but except for a single character this form 

 and typica are very much alike. The two are practically identical in habit, odor, and 

 other general features. Subspecies parishi is not "mainly herbaceous" as Gray was 

 led into supposing from the nature of the types, which were only the hurriedly gathered 

 tops of the plants. The chief distinguishing mark is the villous or almost arachnoid 

 pubescence of the achenes. This often is accentuated in a misleading manner through 

 the viscid nature of the surface glands, which catch and hold the loose tomentum of 

 the involucre during the process of dissection, so that the achenes appear more copiously 

 pubescent than they really are. The leaves are much narrower than in typical tridentata 

 and there is a much larger percentage of entire ones. In these respects parishi is quite 

 similar to the extremely narrow-leaved form of tridentata once named by Gray as variety 

 angustifolia. The panicles are often profuse, with widely spreading and recurving or 

 even pendant branches. Some of the specimens of the type collection exhibit this tend- 

 ency to a limited extent, while others have erect branches. Plants with drooping 

 inflorescence mingle with those in which the panicles are narrow and strictly erect, the 

 other characters remaining unchanged (for example, Piru Creek, October 20, 1919, 

 Hall). This feature is not of specific value, as is indicated by the fact that a parallel 

 variation occurs in A. tridentata typica. In specimens otherwise exact typica, the drooping 

 of the panicle branches is sometimes very evident (Carroll Creek, Sierra Nevada Moun- 

 tains, California, Museum of Vertebrate Zoology; Nighthawk, Washington, October 4, 

 1911, Jones). Along sandy banks of irrigation canals and other streams in northwestern 

 New Mexico the plants of typica often display beautifully pendant sprays of flowers 

 {Hall 11124 UC), and in alkaline soil of northern Nevada dwarf plants have been found 

 to exhibit the same feature, perhaps as a result of frequent browsing {Hall 11235, UC). 

 All of the specimens of parishi thus far collected in Antelope Valley, California, have 

 much condensed and irregular inflorescences, this perhaps indicating a different strain 



