PLANT srcCKSSION IN WASHINGTON 



277 



bunches occurred the low aiuuuil, Festuca pacijica, averaging 150 

 individuals to the quadrat, while small bunches of Poa sand- 

 bergii, and single plants of Plantago purshii averaged 10 per sq. 

 m. each. Dwarfed specimens of EpUohium paniculatum and 

 Clarkia pulcheUa were represented by 18 and 28 plants per sq. m. 

 respectively. Polygonum ma jus gave an average of 2; while 

 Madia exigua with 3 plants per quadrat and Allium acuminatum 



Fig. 1. Station No. 1, in the bunchgrass-rimrock association near Colfax, 

 Washington. 



with 2, were the only other plants represented by an average of 

 more than one specimen per unit area 



At station No. 1, half way up the north bank of the canyon, 

 an atmometer was installed on May 7 (fig. 1), and on the same 

 day another was placed in the pine association on the opposite 

 side of the canyon. Two weeks later a second porous cup was 

 placed near each of these respectively, and at the same time one 

 was installed in the prairie. These were kept in constant oper- 

 ation until September 10. 



