314 RYDBERG: PHy APHICAL NOTES 
c. PACIFIC SPECIES, WHICH HAVE INVADED THE NORTHERN 
ROCKIES, BUT NOT THE SOUTHERN 
1. SPECIES WHICH HAVE REACHED ONLY THE SELKIRK-BITTERROOT 
DISTRICT 
a. Forest species 
The species listed here have probably followed the mountain 
chains in their migration from the Pacific Mountains by the way 
of the Cascades and the Selkirks into the Rockies. 
Trees 
Strobus monticola Tsuga heterophylla 
Larix occidentalis Thuja plicata 
Abies grandis Taxus brevifolia 
Shrubs 
Ribes nevadense Azaliastrum albiflorum 
Rubus nivalis Vaccinium parvifolium 
Rubus spectabtls Linnaea longiflora 
Ceanothus prostratus 
Herbs 
Carex laeviculmis Cytherea occidentalis 
Unifolium dilatatum Corallorrhiza Mertenstana 
Allium validum Trautvetteria grandis 
Disporum oreganum Mitellastra caulescens 
Clintonia uniflora Pectianthia Brewert 
Piperia multiflora Therophon majus 
Piperia elegans Chimaphila Menziesu 
Lysias Menziesti Castilleja pinetorum 
Eburophyton Austinae 
b. Water and bog plants 
These have probably followed the Columbia River and Frazer 
River and their tributaries up into the mountains. 
Shrubs or trees 
Salix Lemmoni Salix sitchensis 
