A. MACROBOTRY8. 57 



RELATIONSHIPS. 



The relation of A. macrobotrys to A. parryi, its nearest ally, has been discussed under 

 the latter, since it is the derived form. The only other American species with which it 

 is connected is A. norvegica, but the connection is not very close. The most striking 

 difference between the two is in the foliage. In macrobotrys the primary divisions of the 

 leaves spread nearly at right-angles to the rachis, while in norvegica they point forward, 

 and the shape of these divisions is different, as shown in the illustrations. The heads, 

 and especially the disk-corollas, of the former are much smaller than in any variety of 

 norvegica, except a few which are otherwise very different. 



A much closer ally is found in A. laciniata Willdenow (Sp. PI. 3:1843, 1804), a species 

 of similar distribution in Siberia, but not known in America. There is a striking similar- 

 ity in habit and foliage and especially in the strongly divergent primary divisions of the 

 leaves. Ledebour (Fl. Rossica, 2:582, 1844-46) states that in laciniata these segments 

 are all reflexed-divaricate, and uses this as one of his distinguishing features. It may be 

 expected, however, that more copious material will show all degrees of divergence. It is 

 even possible that macrobotrys will eventually again become a variety of laciniata, as 

 Willdenow once treated it (Sp. PI. 3: 1843, 1804, as A. laciniata 0), but the evidence 

 at hand does not justify this. The distinguishing characters, as far as indicated by 

 available collections, may be set forth as follows: 



AHemisia macrobotrys Ledebour. 

 Primary divisions of the leaves widely divaricate but 



Artemisia laciniata Willdenow. 

 Primary divisions of the leaves mostly reflexed divari 



cate. 

 Petiole wide and plainly canaliculate. 

 Involucre 3 mm. high, 4 mm. broad. 

 Disk-flowers 25 to 30. 

 Disk-corollas 1.5 to 2 mm. long. 



never reflexed. 

 Petiole slender and obscurely if at all canaliculate. 

 Involucre 3 to 4 mm. high, 6 to 7 mm. broad. 

 Disk -flowers 30 to 50. 

 Disk-corollas 2 to 3 mm. long. 



While additional collections will certainly necessitate modifications of the above 

 diagnoses, it is hoped that the differences here tabulated will serve to distinguish these 

 two closely related species. Both of them exhibit much variation in minor characters. 

 Thus, in writing of macrobotrys as it occurs in Siberia, Ledebour (1. c.) says: 



" Variat foliis glabriu.sculis et plus minus pilosis; laciniis latioribus et angustioribus, longioribus et brevioribus 

 remotioribus et approximatis; rachi plus minus late alata et dentata; corollis pilosiusculis et nudis." 



Similar variations may be expected among American plants, but since the area of 

 distribution is here much smaller than in Asia, it is probable these are not so marked. 

 Detailed descriptions of macrobotrys are given by Ledebour in connection with the original 

 description and the species is figured by him (Ic. Fl. Ross., pi. 467). 



From the above considerations it seems fairly certain that macrobotrys, laciniata, 

 and parryi form a close natural group, and that norvegica is a related species less closely 

 connected. Of these, macrobotrys is perhaps the most primitive. The characters of 

 laciniata, especially the extreme development of the tendency toward reflexed leaf- 

 divisions and the reductions in heads and flowers, indicate this as a derived species. 

 Similarly, parryi may be regarded as a derivative from macrobotrys with reduced heads 

 and flowers. Its geographic position at outlying stations would support this view, but 

 the tendency of its leaf-segments to point forward in some specimens indicates that it may 

 have separated from the parent stock before the character of divergence had become 



thoroughly fixed. 



ECOLOGY AND USES. 



Nothing is known of the ecology or uses of this species. 



5. ARTEMISIA NORVEGICA Fries, Novit. Fl. Suec. ed. 1 : 56, 1817. Plate 3. 

 Boreal Sagewort. 



A perennial herb with a cespitose caudex or short rootstock, 1 to 5 dm. high or much 

 reduced in Arctic forms, mildly fragrant; stems densely clustered, simple up to the 



