110 GENUS AETEMISIA. 



The abundance of the species here and its practically continuous distribution over the 

 greater part of its range accounts perhaps for its failure to develop divergent , forms. 

 Table 8 shows that the extent of variation in characters usually employed for taxonomic 

 segregation is not great. It will be noted also that the variation is quite as extensive 

 in plants growing close together as when they are selected from widely separated locali- 

 ties. This is seen in the sixth entry.where the figures represent the extremes of 8 plants, 

 all gathered on the plains at East Denver, Colorado, from an area of only a few hectares. 

 The variation here is about as great as between the other collections Usted, showing that 

 there is no tendency towards a segregation of forms in the territory covered by this 

 test. 



ECOLOGY. 

 Artemisia frigida is a perennial mat-forming herb, often with a more or less woody 

 base. It is one of the most characteristic autumnal societies of the mixed prairie, 

 ranking second only to Gutierrezia sarothrae. Its abundance in the climax is partly a 

 consequence of grazing, and is due to the position of the leaves in a mat. As a result 

 it is one of the chief indicators of overgrazing on the Great Plains, usually mixing with 

 Gutierrezia in the central portion, exceeding it in the northern part, and falling far 

 below it in abundance in the south. In fallow and abandoned fields it often forms a 

 nearly pure consocies, subclimax to the grass dominants. In its behavior to disturbance 

 it is similar to A. campestris and A. dracunculus, with which it is often associated. 



USES. 

 The prairie sagewort is reported by stockmen and foresters as furnishing an important 

 supply of forage in late fall, winter, and early spring. According to Macoun, it is of 

 great economic importance as a forage plant in Canada (N. Am. Fauna 27:534, 1908), 

 but in the Plains States, where there is a better supply of other range plants, it is re- 

 garded as a weed. It has been used medicinally to some extent in the Rocky Mountain 

 States under the names of Sierra salvia. Rocky Mountain sage, and wild sage. A cold 

 infusion was prepared and this administered as a diuretic and mild cathartic, but it is 

 now largely replaced by other drugs. The constituents have been studied by Rabak 

 (U. S. Dept. Agr. Bur. Plant Ind. Bull. 235:21, 1912). This investigator found that 

 the herbage contained 0.41 per cent of a very fragrant essential oil at the period of 

 flowering, and 0.26 per cent after blossoming. Rabak reports that the oil contains 

 borneol camphor and cineol (eucalyptol), both of which have valuable antiseptic qualities; 

 also some fenchone and both free and combined acids. He makes the suggestion that 

 Artemisia frigida be planted for medicinal use and for use in the manufacture of cellu- 

 loid; also as an ingredient for medicinal soaps or as a scenting substance. The pollen, 

 which is smooth and 3-lobed, is the cause of some of the most severe cases of hay-fever 

 in the districts where the plant is abundant. It therefore enters into pollen therapy as 

 a preventive (see A. vulgaris, p. 100). 



18. ARTEMISIA SCOPULORUM Gray, Proc. Acad. Phil. 1863:66, 1863. Plate 12. 

 Dwarf Sagewort. 



A perennial herb with a slenderly branched or cespitose rootstock, 1 to 3 dm. high, 

 mildly odorous; stems several or numerous, simple up to the inflorescence, erect, mod- 

 erately leafy, faintly striate, lightly tomentulose or glabrate, sometimes becoming 

 reddish; basal leaves crowded, petiolate, 2 to 3.5 cm. long including the petiole, ovate 

 to obovate in outline, mostly twice pinnately parted or divided into narrowly linear or 

 linear-oblanceolate divisions, about 1 mm. wide, silky-canescent ; upper leaves much 

 reduced, less parted, those of the inflorescence often simple, silky like the lower; in- 

 florescence (of 5 to 25 heads) raceme-like, congested towards the summit, 2 to 10 cm. 



