PRAIRIE PLANTS OF SOUTHEASTERN WASHINGTON 283 



which tapers gradually to the end. The larger laterals (if any) 

 are often thrown off within the first 18 inches of soil. These are 

 branched to the third order, and may run off in a rather hori- 

 zontal direction. The tap grows directly downward and is 

 sparingly branched all the way to and at the tip. The main 

 root is not usually more than 0.5 inch in diameter. It changes 

 in color from light yellowish near the surface to nearly white 

 below three feet. It has a sharp bitter taste and lacks the odor 

 so characteristic of Helianthella roots. Twelve roots on a north- 

 east slope averaged 5 feet and 3.4 inches in depth; twelve on a 

 southwest slope 5 feet and 4 inches; and ten on a northwest slope 

 5 feet and 8.2 inches. 



Lithospermum ruderale 



These plants occur as isolated individuals, but their large 

 size, densely tufted leaves, and numerous if not showy flowers, 

 make them conspicuous objects in the bunchgrass association 

 of the rim-rock as well as in the prairie. 



Five root-systems were examined. The large tap roots, from 



3 to 10 inches in circumference, give promise of deeper root- 

 systems than are actually attained. Only one plant reached 

 a depth of 6 feet and 3 inches, and the average depth was only 



4 feet and 10.3 inches. Large laterals were sent off from the 

 main root at various depths from 1 to 2 feet. These ran hori- 

 zontally several feet before turning downward. One main root 

 curved and twisted a great deal finally ending 3 feet northwest 

 of the place where it started. The tip of the largest root examined 

 had decayed. These roots have a very thick cortex, which sepa- 

 rates easily from the stele. The outer part of the cortex is bright 

 reddish especially on the parts below 1 foot. The old root bark 

 is shreddy and gray, but firm. A peculiar taste and odor 

 characterize these roots. Two p'ants on a northwest slope each 

 reached a depth 16 inches greater than any examined on north 

 or south slopes. 



