62 



ROOT DEVELOPMENT IN THE GRASSLAND FORMATION. 



only poorly rebranched. A glance at figure 25 shows that while some absorp- 

 tion takes place in the deeper soil, most of it is confined to the first 2 or 3 feet. 

 In fact, the tap-root below 4 feet is usually poorly supplied with laterals. 



Fig. 25. — Underground portion of Chrysopsis hispida. 



Pentstemon ambiguus. — This diffusely branched perennial is widely dis- 

 tributed over the plains from Colorado to Texas and westward to Utah and 

 Arizona. Its flowering habit from May to September, together with its great 

 abundance, often causes it to form conspicuous societies. The specimens 

 examined were bushy plants, 1 to 1.5 feet in diameter and about 1.3 feet high; 

 they were in fruit. The individual plants are connected by strong, woody 

 rhizomes, 4 to 8 mm. in diameter, and from 3 to more than 12 inches in length. 

 These are densely matted and twisted. From the rhizomes, especially under 

 the clumps, arise clusters of roots. Some have a diameter of 8 mm., but most of 

 them are only 2 to 4 mm. thick. Like the rhizomes, they are reddish-brown in 



