324 RYDBERG: PHYTOGEOGRAPHICAL NOTES 
Arabis oreophila Swertia congesta 
Arabis exilis Synthyris laciniata 
Micranthes Greenet Orthocarpus Tolmiet 
Potentilla ovina Aster amplifolius 
Drymocallis foliosa Machaeranthera viscosa 
Trifolium scariosum Erigeron tenellum 
Angelica Roseana Arnica arcana 
Dodecatheon salinumt 
The following reach the Black Hills: 
Alsinopsis dawsonensis Aragallus gracilis 
Atelophragma glabriuscula Aragallus spicatust 
Atelophragma Forwood11 Aster meritus 
Homalobus dispar Cirsium Drummondii 
Aragallus villosus 
2. SPECIES FOUND IN MONTANA AND NORTHERN IDAHO AND 
NORTHWARD 
This category contains one tree, Betula subcordata, two shrubs 
(Vaccinium sp.), and 31 herbs; altogether 34 species. Of these, 
Aragallus splendens extends eastward to Minnesota, Vaccinium 
membranaceum to upper Michigan, and V. ovalifolium to the Gaspé 
Peninsula. 
3. LOCAL SPECIES OR SPECIES OF VERY RESTRICTED RANGE 
The local species of Wyoming and eastern Idaho number 47 
(of which perhaps one third should be accredited to the Southern 
Rockies while 6 are also found in the Uintahs or Wasatchs), those 
of Montana 19, those of western Idaho 14, those of the Black 
Hills 5, and those of the Canadian Rockies 22 (among the latter one 
tree, Betula alaskana, and three shrubs); in all, 107 local species. 
If all categories of endemic species are considered, the number 
restricted to the Northern Rockies includes altogether about 230 
species, and the number endemic to the — Mountains as a 
whole 1,040 species. 
SUMMARY 
Within the Montane Zone in the Rocky Mountains are found 
about 1900 species. Of these, approximately 50 per cent* are 

* All percentage figures in the following paragraphs are computed with reference 
to the total number of species. 
