A. CAMPE8TRI8. 129 



assemblage, but in all essentials it is so close to some of the other subspecies, especially 

 the tall (bourgeauana) forms of spithamaea that a workable key can not be constructed 

 that will satisfactorily separate it. It is undoubtedly a derivative of some boreal form 

 which has become isolated and has responded to protection and the more genial climate 

 through the development of an exceptionally robust habit and other characters espe- 

 cially suited to its southerly maritime habitat. This view finds some substantiation in 

 the fact that while the plants of the middle California coast represent the extreme type 

 as to robustness, enlarged inflorescence, and spreading pubescence, those from farther 

 north have these characters much less developed. Thus, a collection from Lake Earle, 

 Del Norte County, California (Univ. Calif. 128619), has sparsely leafy stems only 2 dm. 

 high and leaves small in proportion, while the inflorescence is spike-like and only 1.2 cm. 

 broad at the broadest place. These plants have the whole aspect, although not quite 

 the pubescence, of some forms of spithamaea. 



Another collection {Tracy 3023) from the next county south of Del Norte is interme- 

 diate in these characters between the Lake Earle collection and the common form of 

 middle California. The northern ancestor of this subspecies is perhaps to be found 

 in spithamaea, of which some forms are 2 to 3 dm. high and with an inflorescence 1 to 4 

 cm. broad, thus completely overlapping the dimensions of pycnocephala. In pubescence, 

 also, they are scarcely distinct from this coastal plant, so that if it were not for the 

 habitat they would quite certainly be called the same. Such plants come from sandy 

 river banks at Bingen, Klickitat County, Washington (Suksdorf 2685 and 2686, both 

 at the National Herbarium, where determined as A. ripicola Rydberg). It is also of 

 interest to find that a variety with some of these characteristics has been recognized 

 in plants growing on sandy shores in France. This is described as a stout plant with 

 short and broad leaf-segments and comparatively large heads. To it has been given 

 the name, A. campestris var. maritima Lloyd (see Coste, Fl. France 2:333, 1903). 



The relationships of the subspecies of A. campestris are graphically represented in the 

 accompanying diagram (p. 127). 



ECOLOGY. 



Artemisia campestris is typically a rosette-former, though this habit is more marked 

 in the biennial than the perennial forms. For the most part the subspecies are serai 

 dominants, but pacifica in particular is an important society of the mixed-prairie climax. 

 Typica, caudata, and pycnocephala regularly form consocies or socies on sandy shores 

 and dunes, from which they sometimes find their way into waste places. Pacifica is 

 one of the most unpalatable of Artemisias to stock and hence is excelled only by A. 

 frigida as an indicator of overgrazing. The pioneering quality of the species is also shown 

 in the frequent occurrence of pacifica in disturbed soils, especially sands and gravels. 



USES. 



The field sagewort is a common weed on many of the stock ranges of the West, espe- 

 cially in the northern Rocky Mountain States, but it is so unpalatable that it is grazed 

 only when all other sources fail. It occasionally tides animals, especially sheep, over 

 exceptionally hard seasons, but its value for this purpose is slight. In these same regions 

 the herbage is gathered, dried, and placed upon the market as a substitute for imported 

 sage, used in cookery and somewhat in medicine, and the name of "wild hair tonic" 

 sometimes applied to it indicates that perhaps it is employed to stimulate the growth of 

 the hair. The properties of the essential oil present in the herbage of subspecies caudata 

 have been studied by Rabek (Pharm. Rev. 24:324, 1906). It is one of the causes of 

 hay-fever, as shown by tests made in the Rocky Mountain region. 



