A. CAMPESTRIS. 



127 



sometimes cespitose, and the flowering stems are usually shorter. It may appear desir- 

 able to some to set these forms off as a species distinct from campestris and pacifica on 

 the basis of the larger heads, but a glance at table 1 1 will show the impossibility of this 

 course. In fact, the overlapping is much greater than indicated by the few specimens 

 there reported upon. Neither Besser nor Gray was able to find specific distinctions 

 between canadensis (here included with subspecies borealis) and pacifica. Moreover, 



Fio. 18. — Phylogenetic chart of the subspecies of Artemisia campeslria. 



this last-named subspecies exhibits forms intergrading with spithamaea. For example, 

 3 sheets at the National Herbarium from Glacier National Park (Standley 17307, 17331, 

 17716) represent plants 3 to 5 dm. high and with the usual broad panicle, while another 

 (Standley 16688) from the same park is a dwarf only 1.5 dm. high, the inflorescence less 

 than 1 cm. broad and yet with heads much too small for subspecies spithamaea. The 

 northern subspecies borealis and spithamaea differ between themselves only in very minor 

 characters and in pubescence. It would be entirely logical to unite them, and recognize 

 several ecologic forms, but the marked difference in the appearance of the extremes and 

 the absence of intergrades over certain large areas render the subspecific rank of some 

 use. Still further segregations have been made, but these are based upon habital and 

 other characters now known to be of little taxonomic value. They are here indicated 

 under minor variations. 



The most remarkable deviation within the species is represented by subspecies pycno- 

 cephala, a form restricted to the coastal sands of northern California and southern Oregon 

 and at least 1,000 km. removed from any of the others. Its robust habit and coarse 

 pubescence give to it an aspect so unique that it seems scarcely to belong to the present 



