39 



t 



such as were frankly indebted to human agency for their trans- 

 portation; but the northern boundary of the State, although not 

 the northern boundary of the Flora of the Northwest Coast, 

 seemed worth some study. Along the sand-bars of the Columbia 

 and on its low muddy shores is a surprising aggregation of species 

 that have either been brought down by the river from their 

 inland range, or have found lodgment in some unexplained way 

 after wider wanderings. The number of these unexpected 

 strangers will be evident after a study of the following list. 



In addition to these penetrations of the frontier by indigenous 

 species, the influx of foreign forms has been found to continue 

 unabated. Just where they come from it is usually quite impos- 

 sible to determiine; they were not here yesterday, but to-day we 

 find them, and to-morrow, so favorable are our soil and climate, 

 we can be reasonably certain that they will still be here. Not 

 only is this true in the centers of population, but very often our 

 first encounter with these new plants is in some remote country 

 district or along some mountain stream. No species has been 

 included in the following list that was not growing spontaneously 

 and with a good chance of perpetuating itself indefinitely. Every 

 one of these species was collected within the Oregon limits of the 

 Flora of the Northwest Coast, and is understood to be without 

 mention in that work. Specimens of each have been deposited 

 in the Gray Herbarium, and I must again express my indebted- 

 ness to Mr. J. Francis Macbride for his unwearying kindness in 

 revising and correcting my attempts at determination, as well 

 as in clearing up many knotty problems of nomenclature and 

 specific limits. Species that are clearly introduced are marked 

 with an asterisk(*). A number of these were originally reported 

 in my list of Linnton ballast-plants (Torreya 17: 151-160). 

 At the time they did not seem sufificiently stable to be worthy of 

 inclusion in a list of established species; but, although the area 

 was occupied by a shipyard during the war, and the vegetation 

 upon it consequently subjected to a very rigorous test (most of 

 the ground being excavated or planked over, covered with piles 

 of material and machinery, and tramped over daily by hundreds 

 of men and horses), I was delighted to find that several species 



