50 



ROOT DEVELOPMENT IN THE GRASSLAND FORMATION. 



Mentzelia nuda. — This tall, coarse, somewhat woody herb is a species of 

 rather wide distribution throughout the drier portions of the grassland forma- 

 tion. It is often locally abundant and forms marked societies when the large 

 yellowish-white flowers are in bloom during July and August. Three large 

 plants were examined on the well-covered rim of a blowout. The largest had 

 a tap-root an inch in diameter, from which arose 4 erect stems over 2 feet high. 

 The crowns of all three plants were more or less decayed and somewhat spongy 



Fig. 19. — Haplopappus spinulosua. 



