PIPER FLORA OF THE STATE OF WASHINGTON. 67 



THE COLUMBIA GORGE. 



The wonderful <2:org'e of the Columbia liiver (PI. XVIII), extend- 

 ing a distance of about 50 kilometers. (38 miles), presents peculiarities 

 scarcely paralleled elsewhere in the Pacific northwest. The cliffs, ris- 

 ing hundreds of meters verticall}^ present almost every rupestrine con- 

 dition. Some of them are in almost perpetual shadow, others sub- 

 jected to bright sunshine. Some become dry almost with the cessa- 

 tion of the spring rains, others are bathed constantly in tlie spray of 

 waterfalls. There are thus furnished suitable conditions, both to 

 species from the arid interior and to others that normally flourish 

 only in cool mountain valley^. The resultant association of Cana- 

 dian or even Hudsonian species with those of tlie Transition zones is 

 strikingly i)ecvdiar. 



That such an unusual environment sliould be llie habitat of a con- 

 siderable mnnber of species not found elscAvhere might have been 

 predicted. Xo less than IG species are practically confined to this 

 region. They are: 



Ayrostis lioirclUi. Loniut'nnii sp. nov. 



CaJutnaiintHtix Jioircllii. Mini ill ns alf^iiioidcs. 



Dclphbiiinii troUi'ifoJimu. rciitstciiioii harrcttac. 



Dodecathroii ilciitiitinn. I'oa in iilfiioiinir. 



Er'ujeron hoircUil. ^iiUiruntia orci/aiiu. 



Erif/eron ofei/ainis. TcUinid odorata. 



Hcmicra violacra. YulcridiiclJa aplnnwptcra. 



Ilicraciiiiii Ioii(iihrrh(\ Vihiniiinii clliiiliciiiii. 



Some few others are worth}- of special mention. Bolandra orerjana^ 

 otherwise confined to the Columbia gorge, reapjiears on the bluffs of 

 Snake Eiver in AA^illowa County, Oreg. 



Synthyris reniformis^ abundant on the Oregon siile of the gorge 

 almost at the river's edge, has its real home in the Canadian and Hud- 

 sonian zones of the Blue and Bitterroot mountains. Like several 

 other species, it does not occur on the Washington side t)f the Colum- 

 bia gorge. 



A number of the Canadian and Hudsonian species that descend 

 into the Columbia gorge are more or less modified from their original 

 forms and may be regarded as subspecies, when compared with the 

 alpine forms. Such are: 



Romaiizoffia sitcliensis. Saxifraya occidentalls. 



Saxifraga hroiichialis. Valeriana sitcheiisis. 



Saxifraga caesp itosa. 



But a larger number preserve their identity beyond question. Such 

 are: 



Carcx macrochaeta. rcntstemon diffu-'^iis: 



Vhelone neniorosa. Pentstenion rupicoht. 



Cornus canadensis. Polypodium licsperiam. 



Doiiglasia laevigata. Tofleldia intermedia. 



