188 BOTANICAL GAZETTE [SEPTEMBER 
fig. 15 grew in sandy soil on the mesa. The root system is charac- 
terized by a tap root which is poorly differentiated or even absent, 
and very prominent laterals. The remains of the crowns of several 
years are shown. When the plant grows in an unstable situation, 
Vv __ such as the rapidly eroding side of an 
arroyo, vegetative reproduction from 
the roots occurs very commonly, 
enabling the plant to maintain a 
foothold. 
Berlandiera lyrata—This plant is 
confined almost entirely to the sides 
of arroyo beds. The root system has 
a stout tap root with very few 
laterals. The group of laterals near 
the surface of the ground in so many 
plants of the region is absent here. 
The entire root system is thick and 
fleshy and the upper portion is 
swollen to the thickness of an inch. 
Plant A, fig. 16, grew about 1 it. 
_ above the bed of anarroyo. The tap 
_ root divided into two horizontal ~ 
_ branches slightly below the level of 
ie arroyo bed. Plant B grew about 
4 ft. above the bed of an arroyo and 
bore no extensive laterals until it 
_ reached the level of the bed of the 
\ arroyo, where it branched freely. 
1 i - cei of the re root is — 
cg : tance to - the layer of n moister soil Oe . 
