REPRODUCTIVE ORGANS 



Fig. 120. A common tumbleweed ( Cydolomd). 



of pine and catalpa. Plumes and tufts of hairs are devel- 

 oped by the seed-like fruits of dandelion, thistle, and ver)- 

 many of their relatives, and by the seeds of the milkweed 

 (see Figs. Ill, 112, 113, 114). On plains, or level stretches, 

 where winds are 

 strong, a curious 

 habit of seed dis- 

 persal has been de- 

 veloped ])y certain 

 plants known as 

 " tumbleweeds " or 

 ''field rollers." 

 These plants are 

 profusely branching 

 annuals with a small ^ , , ^ 



Fig. 121. The 3-valved fruit of violet diBcharging 

 root system m a its eeedB.-After Bfat.. 



