314 RYDBERG: PHYTOGEOGRAPHICAL NOTES 
c. PACIFIC SPECIES, WHICH HAVE INVADED THE NORTHERN 
ROCKIES, BUT NOT THE SOUTHERN 
I. 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 spectabilis Linnaea longiflora 
Ceanothus prostratus 
: Herbs 
Carex laeviculmis Cytherea occidentalis 
Untfolium dilatatum Corallorrhiza Mertensiana 
Allium validum Trautvetteria grandis 
Disporum oreganum Mitellastra caulescens 
Clintonia uniflora Pectianthia Breweri 
Piperia multiflora Therophon majus 
Piperta elegans Chimaphila Menziesii 
Lysias Menziesii Castilleja pinetorum 
Eburophyton A ustinae 
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 
