SOURCES OP THE VEGETATION 



73 



Salix Mackenzimia 

 " exigua 

 " Scmileriaiia 

 ' ' glaucops 

 Betula fontinalis 

 Odostemon Aquifolium 

 I\iibiis parviflorus 

 Amelanchier aJnifolia 

 Crataegus Douglasii 

 Primus demissa 

 Pachystima Myrsiiiites 



Phyllodoce glandulifera 

 Menziesia ferruginea 

 Kalmia polifolia 

 Cassiope Mertensiana 

 Ganlfheria humifusa 

 V arc ill ium mcmhranaceum 



' ' oreophilum 



' ' scoparium 

 Ai'iemisia camporum 



' ' frigida 



" cana 



Rhus Rydbergii 



The following species seem to have entered from the soutli- 

 ern Rockies or the Great Basin: 



Yucca glauca 

 Atriplex truncata 

 Sareobatus vermiculatus 

 Eurotia lanata 

 Grayia spinosa 

 Bibes aureum 

 Rosa Feiidleri 



" ultramontana 

 Cercocarpus ledifolius 



' ' montanus 



Purshia tridentata 

 AmelancJiier oreophila 



Opuntia polyacantha 

 Mammillaria missouriensis 



" vivipara 



Gilia pungens 

 Sambucus glauca 

 Aplopappus suffruticosus 

 Teiradymia cavescens 



" spinosa 



Chrysothamnus nauseosus 



" viscidiflorus 



Artemisia tridentata 

 " spinescens 



" utahcnsis 



Yucca is a common plant in many localities on the plains 

 of eastern Montana. It is usually found on the slopes of the 

 foothills or benches. On the other hand Opuntia polyacantha, 

 also plentiful in the same region, is more abundant on the lovi? 

 flat benches. The most interesting species in the above list is 

 the mountain mahogany, Cercocarpus ledifolius, -which, is found 

 as far north in the Rocky Mountains as Helena. It is plentiful 

 about the head of the Bitter Root Valley v^'here it has apparently 

 arrived from the hills of southern Idaho across the Bitter Root 

 Range. Purshia probably came from the same source but is 

 somewhat more widely distributed through the Bitter Root Val- 

 ley and sparsely farther north in the Flathead Valleys and 



