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ADDITIONS TO THE FLORA OF WESTERN OREGON 



DURING 1922 



James C. Nelson 



The outstanding feature of the past season's collecting in 

 this region has been the number of new species afiforded by the 

 river-shores. It is not specially surprising to find species of the 

 interior basin along the shores of the Columbia about Portland, 

 brought down during the annual inundation; but it is much more 

 difficult to explain the frequent occurrence of introduced species 

 along the Willamette and its tributaries. These rivers rise in 

 mountainous and sparsely-settled regions where the flora is 

 strictly indigenous; and the foreign species occurring so abund- 

 antly along their shores are usually never found about the towns 

 along the banks. Here at Salem we have a very distinct 

 riparian flora, largely made up of introduced species which are 

 never seen above high-water mark. The most frequent com- 

 ponents are: Saponaria officinalis L., Cheno podium Botrys L., 

 C. ambrosioides L., Datura Stramonium L., D. Tatula L., Solanum 

 nigrum L. var. villosum L., Aristida oligantha Michx. and 

 Cyperus esculentus L. ; yet none of these species are found as 

 weeds about the towns along the upper river. Most of these 

 are folind along the Santiam also, with the addition of Aspris 

 capillaris (Host) Hitchc, Lychnis alba Mill., Scleranthus annuus 

 L., Chrysanthemum Parthenium. L. and Cynoglossum officinale L. 

 The sand- and gravel-bars along these rivers seem botanically 

 speaking to be a sort of extended ballast-ground, and the col- 

 lector may feel assured of a surprise on almost every visit. The 

 28 species of the present list, all of which were growing spon- 

 taneously, verify the earlier prediction that a more careful 

 study of our region would raise Piper & Beattie's total of 161 7 

 species to at least 2000. These 28 bring the total now presented 

 in these annual lists to 399. Added to the 161 7 of the Flora of 

 the Northwest Coast, the 2000 mark has been exceeded by 16 

 species. Nor is there any reason to suppose that another season 

 will not result in still further additions. Species plainly intro- 

 duced are marked * in the following list: 



I. Equisetum laevigatum A. Br. In cultivated ground under 

 fruit-trees in the Willamette River bottoms near Keizer school- 

 house, four miles north of Salem. Determined by W. R. Maxon. 



