' 



KESEMBLANCE OP DESERT AND HIGH MOUNTAIN VEGETATION. 55 



perature would be fatal to a growing plant of ordinary structure. It 

 is undoubtedly true that the hairy covering, and perhaps also some 

 other structural characteristics of desert shrubs, have the effect of molli- 

 fying these conditions. The subject is one that invites and requires 

 experiment. It should be pointed out here that the depressed vegeta- 

 tion near timber-line on high mountains exhibits epidermal structures 

 very similar to some of those which occur in the desert. The densely 

 candescent Lupinus breweri and Raillardella argentea of the Mount 

 Whitney region may be cited as examples. The temperature at these 

 altitudes is seldom or never extremely high, but the conditions of clear 

 air and consequent rapid radiation at night exist here precisely as in 

 the desert. There can be no doubt that the primary function of these 

 modifications has reference to the regulating of temperature rather than 

 the regulating of moisture. 



CATALOGUE OF SPECIES. 



RANUNCULACE.S!. 



Clematis ligusticifolia Nutt. in Terr. & Gr. PI. i. 9 (1838). Type locality, 

 "pi-linn of the Rockv Mountains, in open and in bnsby places, near streams." 1 



A Clematis without flowers or fruit was abundant along streams in several canons 

 of the Panamint Mountains. It is undoubtedly a form of this species. 



Thalictrum alpinum L. Sp. PI. i. 545 (1753). Type locality European. 



Along Cottonwood Creek, White Mountains (No. 1806). This circumpolar species 

 extends southward on the Atlantic side of the hemisphere to Anticosti and Newfound- 

 land, and along the Pocky Mountain system to Colorado, Nevada, aud Utah. It is 

 now reported for the lirst time in California. 



Thalictrum fendleri platycarpum Trelease, Proc. Post. Soc. Nat. Hist, xxiii. 304 

 (1886). Type locality, "California." 



This has been separated from T. fendleri as a distinct species ■ mainly on 

 account of differences in the pubescence and in the sepals. It appears, however, that 

 the form and texture of the sepals vary considerably in T. fendleri. The pubescence 

 of New Mexican specimens of that species appears under a lens densely and minutely 

 scar* or frranulose, while the Californian plant appears glabrous with the exception 

 of its eland-tipped hairs. A surface similar to this is possessed by most specimens 

 of T fendleri from Colorado. An examination of all these with a compound micro- 

 scope shows that the apparent difference is one of degree, not of kind. In the Cali- 

 fornian and Colorado plants the outer surface of each epidermal cell is only moder- 

 ately convex, while in the New Mexican plant the surface has apparently protruded 

 into a knob with a constriction at its base. So closely set are these knobs that they 

 forma complete coating over the leaf surface. Between these two extremes all 

 gradations may be found. On Frazier Mountain (No. 1204), and near Mineral King 



(No. 1387). ___ 



" ' In quoting NoTtli American type localities a literatim copy of the original text is 

 eiven the only variation being in the non-capitalization of the initial letter, m a 

 uniform use of Roman instead of italic letters, and in the omission ot diacritic marks. 

 If the work containing the original description could not be consulted, all reference 

 to the type locality is omitted. 

 *Pitt. i. 106 (1888). 



