66 KOK'KST DISTRIIM TION 



Southwest and the Mexican Plateau may he regarded as ex- 

 amples. The representatives of these irroups in the -Montana 

 flora <-an he regarded only as having a southern origin. With 

 such {xiints in mind a uronpinir of species is attempted accord- 

 ing to the sources from which they seem to have migrated into 

 tlie northern Rocky Mountains. 



The following species mostly have a northern transcontinent- 

 al range and appear to have moved southward aloni: the Rocky 

 Mountains into Montana and in some eas; i s far beyond: 

 *Jiuninnts cotunnuiis DasipJiora frnticosa 



* " Sabina Elaeagnus argent r a 



riiftuhis i r< tuuloidi x Lepargyraea c<nnnl< 



Imlsitni'fi i'<i liliiis (jlubra 



Stili.r cm-flat a Ifluinuius <il iiifolto 



" ('li/oro}>lnjll<t Ctinius xtnlmtiff nt 



" fluviatilis . cdiiadf nsls 



" Bcbbiana Andromeda poli folia 



" Barclaiji *Arctostapkylos rm 



" pseudomyrsinites Chiogenes hispidula 



Hi tula fxipi/n'fcra *Vaccin him uliginosum 



*AInn.<< ii'cdi'fi caespitosum 



Ribes lacustre oral i folium 



" liuflsfin;iinum Rambiicus raccmosa 



Hi' bus sfrif/'is'is ^f/niftharicarpns /HI uc if lor its 



Rosa acicularis Loniara hirohicrtitu 



There is, of course, no barrier to the southward movement 

 of species alon-j this hi'j'hway throiiL-'h the region here under con- 

 sideration. Five of the ;ibove species (marked *) occur ai-ound 

 the world in the northern hemisphere. Most of the others are 

 middle or northern Atlantic Coast or eastern species which 

 apparently have extended their ranges far to the northwest, 

 ,'j north of the (In-.-it 1'lains to the Rocky Mountains and 

 tli-nrr -miihwjird : some are extensively distributed from the 

 coast of \i-\\ Kmjhmd and Labrador to Alaska. 



The following have entered Montana and the Rocky Moun- 

 tains fn.m the e;i.st : 



lug angUSttfolia I'nums tiunricmm 



>'//'/' "H> Acer \ifiundo 



indict I'- Sam/melts rnmidi HSI'S 



