LESSONS WITH PLANTS 



33'^ 



a scale and large pistil. These flowers, compared wilh a 

 flower like a rose, are very incomplete, yet they have the essen- 

 tial things necessary for seed making. The pistillate cat- 

 kins become long clusters of green berry-like fruit. Later in 

 summer the pods ripen, become papery in texture, and final- 

 ly split open, let- 

 ting out a mass 

 of down-covered 

 seed which floats 

 away. 



Compare with 

 these the flow- 

 ers of trees like 

 the butternuts, 

 walnuts, and 

 oaks. These have 

 staminate flow- 

 ers very similar 

 to those of the 

 willows and cot- 

 tonwoods, but in 

 these the pistillate flowers are not in catkins, but are in clusters 

 of a few or singly, and nearly sessile on the twig. They are, 

 however, rudimentary in structure and do not possess a 

 corolla or stamens. The acorns (ripe ovaries) are set in a 

 scaly cup. Some acorns, hke those of the red oak, require 

 two years for ripening. Hence we find on the fruiting 

 branches pistillate flowers and also year-old acorns, but on 

 wood of different years. 



Study the flowers of boxelders. These are not in catkins 

 but in clusters and drooping masses, each floweret on a sep- 



Fic. 130 



Staminate Catkins of Cottonwood. 

 (Pollen carried by wind.) 



