C. PARRYI. 205 



of parryi as glabrous, of bolanderi as viscidulous. In all specimens of parryi examined 

 the leaves are minutely glandular and often also puberulent. The "glandular-scabrous" 

 character assigned by CJreene to asper is exactly the same as in bolanderi, except that the 

 glands are slightly stalked and thus more prominent. Finally, the reduced number of 

 heads in monocephalus is a reaction to the subalpine environment as indicated by inter- 

 mediate forms at lower elevations {Heller 9976). A similar reduction, although not car- 

 ried to such an extreme, is common in subspecies asper and occasionally in howardi. 



In attempting to trace the lines of evolution within the species it is necessary to keep 

 in mind the facts of geographic distribution as well as the morphology of the various sub- 

 species and minor variations. Thus, the close phylogenetic connection between lypicus, 

 of the Rocky Mountains, and several of the Sierra Nevadan subspecies indicates that the 

 distributional areas of these were in contact during some past period. This may have 

 occurred in or near the area now known as the Great Basin, where the earlier climate was 

 much less arid than that of the present time and therefore better suited to the growth of 

 these mesophytic types. It seems that over this central area there may have grown a 

 primitive form, one with large heads of numerous flowers and bracts, with a well-developed 

 foliage, and with no special structures such as now mark some of the more highly 

 specialized subspecies. Then, as greater aridity set in, this primitive stock broke up, 

 forming two branches. One of these migrated easterly into the Rocky Mountains, and 

 became the present subspecies lypicus, which comes so close to fulfilling the requirements 

 of the original stock just assumed that it is placed at the very bottom in the chart of 

 relationships. The other branch moved to the westward, finally coming to rest in the 

 Sierra Nevada. In the meantime, this western migrant underwent modifications, involv- 

 ing especially a reduction in the number of flowers in each head and also a reduction in 

 the inflorescence itself. These changes resulted in subspecies bolanderi, a wide-leaved 

 shrub now appearing only as a relict in the middle Sierra. It may be assumed that as 

 bolanderi migrated into the western plateaus and mountains its distribution became dis- 

 continuous and that distinct forms were evolved in the different areas. At any rate, there 

 now occurs in the Siskiyou Mountains of northern California a subspecies latior which has 

 all the indications of being a lineal descendant of bolanderi, especially in the still further 

 reduction of the number of flowers. The somewhat better development of the foliage 

 and the more elongated inflorescence may be either persistent traits of a common ancestor 

 or a more recent adaptation to the more humid habitat. A much more striking modifica- 

 tion is subspecies imulus, now stranded in the high mountains of southern California. 

 This is a dwarf with very short, spatulate leaves, commonly colored involucres, and with 

 the whole herbage woolly. The appearance is so unique that one is tempted to give the 

 form specific standing, but it shows no variation from bolanderi in the number or size of 

 flowers and bracts or in any other feature commonly accepted as of specific value. 



The six remaining subspecies probably are all more recent in their origin than those 

 already discussed. This is evidenced by their narrowed leaves, which feature enables 

 them to cope with their more arid environment, and especially by the reduction in the 

 number of flowers in each head. It would be desirable to set off this group as a distinct 

 species (thus preserving the established name of howardi in specific rank) were it not for 

 latior, which, although plainly a derivative of bolanderi, has the flower reduction of these. 

 There is also some doubt as to the naturalness of the assemblage, as will be noted further 

 on. The difficulties in the way of such a treatment are seen also in the key to the sub- 

 species, where no clear-cut division can be made between these and the earlier subspecies. 

 The migratory routes taken by lypicus and bolanderi and their derivatives doubtless 

 were followed by these later subspecies, but most of them did not get so far from the 

 original center of distribution and at least two {nevadensis and asper) still occupy moun- 

 tainous districts well within the Great Basin area. 



