III. ROOT SYSTEMS OF SHORT-GRASS-PLAINS SPECIES. 



Although root excavations of both native and crop plants of short- 

 grass plains have been made at six stations and the dominants 

 thoroughly studied, only two new species in addition to those already 

 reported (Weaver, 1919) are here described. Indeed, the short-grasses 

 usually have such profound control of the area that other grasses and 

 herbs are relatively rare. In the chapter on ecads, the root systems 

 of these dominants will be fully discussed. They have been repeatedly 

 excavated and studied in many localities, not only in the short-grass 

 plains but also in mixed and true prairie. 



Opuntia polyacantha and Schedonnardus paniculatus were examined 

 on the short-grass plains about 5 miles northwest of Sterling, Colorado 

 (fig. 14). The precipitation at Sterling is only about 17 inches. The 

 run-off must be high, for, although much of the ground is bare between 

 the alternating mats of Bulbilis dactyloides and Bouteloua gracilis, the 

 roots extend throughout the surface soil and bind the hard silt-loam 

 into a very compact substratum (plate 2, a). A so-called "hardpan" 



# Ardmore 



V. 



.Seneca 



NEBRASKA 



Central Citv» 



Wahoo 



Sterling 



Lincoln 



Yuma, IfHaigler •Z^ i _ r _ b ALLT_ A 



COLORADO 



Burlington i 



Limon • • • I 



Flagler | 



• Colorado ■ 



Springs 



Phillipsburg 

 .Colby 



,Mankato 





KAN S A S 



Fig. 14. — Map showing stations in the grassland associations where studies of root 

 systems have been made. 



occurs here at a depth of about 2 feet. Aside from the dominant 

 grasses, Opuntia polyacantha and 0. camanchica were the most con- 

 spicuous species. But as in all typical short-grass plains areas (cf. p. 

 109) more or less of Aristida purpurea, Psoralea tenuiflora, Festuca 

 octoflora, Plantago purshii, Artemisia frigida, Schedonnardus panicu- 

 latus, etc., are to be found. The relative abundance and luxuriance 



42 



