INTRODUCTION. 



The following pages aim to give descriptions of all the seed-plants and 

 fern-plants growing wild within the area circumscribed by a circle whose 

 radius is 35 kilometers (21 miles) with Pullman as a center. This area em- 

 braces about 24 townships in Washington and 11 in Idaho. Geographically 

 the limits are approximately marked by vSteptoe Butte and Garfield on the 

 north, Troy on the east, Lewiston on the southeast and Almota on the west. 



The region consists mainly of rolling hills, 30-150 meters high, with an 

 average altitude from the sea-level of 800 meters. These hills are destitute 

 of trees and shrubs, and are typical of a large area in Eastern Washington 

 and Western Idaho. They are generally designated the Palouse Hills, the 

 name said to have been given by the early Jesuit missionaries (French 

 pelouse, greensward). 



Besides these low rolling hills occur others of considerably higher eleva- 

 tion. Steptoe Butte, already mentioned, is a perfectly conical peak of about 

 1200 meters altitude. It is wholly destitute of trees. 



Kamiack Butte is a bold hill, shaped like a sugar-loaf, lying 15 kilometers 

 north of Pullman. Its altitude is about 1 100 meters. The summit and north 

 slopes are heavily timbered with coniferous trees, but the south slope is 

 nearly bare. 



The Thatuna Hills are the highest of a considerable number of timbered 

 mountains that occupy about one-fifth of the area of the circle in the eastern 

 and north-eastern portions. The culminating peak, Cedar Mountain, isabout 

 2000 meters high, and lies 30 kilometers east of Pullman. 



The drainage of the region is mainly north-westward. In the extreme 

 eastern part it is south-eastward. Four streams traverse the region for 

 nearly its full width. The North Fork of the Palouse flows westward through 

 the northern part of the area; the South Fork flows north-westward through 

 the center of the circle, joining the North Fork near the north-eastern limit; 

 Union Flat creek parallels the preceding stream, about 10 kilometers farther 

 southward; and Snake River for 60 kilometers has hewn an enormous canyon, 

 700 meters deep, through the southwestern part. The other three streams 

 form narrow valleys, 50-200 meters lower than the surrounding hills, or in 

 some places narrow canyons. All these streams as well as smaller ones are 

 margined with a growth of willows, poplars, thorns and other shrubs, and 

 occasionally with a few pines. 



The lowest point in the area is where Snake River crosses the western 

 limit, the altitude being about 200 meters. The highest point is the summit 

 of Cedar Mountain, altitude about 2000 meters. 



Geologically the Palouse Hills are formed of the worn surface of an im- 

 mense sheet of basalt or lava-rock. This basalt, as revealed in the canyon 

 of Snake River is at least 700 meters thick and consists of several, probably 



