432 THE VASCULAR PLANTS 



strobili. If we examine cones carefully, we shall learn a 

 good deal about the reproductive methods and structures 

 of gymnosperms. 



A. Two Kinds of Cones. — Pines, and the other Conifers 

 as well, produce two kinds of cones; that is, they have 

 two kinds of strobili. The large hard cones which pro- 

 duce the seeds are composed of megasporophylls. They 

 are sometimes called pistillate cones, because, like the 

 pistils of flowers, they bear ovules. Ovules are megaspo- 

 rangia. 



The other kind of cone is much smaller and softer and 

 does not remain on the tree so long ; it is composed of 

 microsporophylls ; it is called the staminate cone because 

 it produces pollen. Pollen sacs are microsporangia. The 

 staminate cones are usually found on the trees in spring; 

 they are soft, tassel-like structures, more like catkins than 

 like the hard pistillate cones. After they have shed their 

 microspores (better known as pollen), they wither and die. 



B. Pollination. — The pollen of the pines has wings. 

 (See Figure 224.) Great quantities of it are produced. It 

 is scattered by the wind. When the pollen is flying in 

 pine woods, the lumbermen speak of "showers of sulphur," 

 for the great quantities of pollen look like that. Some of 

 the pollen falls on the hard cones, the kind which produces 

 seed. To understand what happens then we must under- 

 stand the structure of the seed-producing cone. (Study 

 Figure 225.) 



The seed-producing or pistillate cones are composed of 

 hard, woody scales which grow close together. When the 

 pollen is flying in the spring, the young cones, which are 



