3o6 



The Living Plant 



in a good many plants, especially trees, and, in lesser degree, 

 shrubs, for these are most exposed to the sweep of the winds ; while 

 it is rare in herbs and confined mostly to those that grow in fully 

 exposed places. In such plants the smooth light pollen grains often 

 possess bladders, or wings providing more surface for action of the 

 wind (figure 108), while, moreover they are produced in vast 



Fig. 108. — Typical pollen grains, highly magnified. On the left next above the bottom 

 row, are three from the Pine, showing the attached bladders. The very rough kinds, 

 especially those of the upper row, are carried by insects, to whose hairy bodies they are 

 thus adapted to cling. (Reduced from Kerner's Pflanzenlehen) . 



quantities to compensate for the inevitable waste inseparable 

 from this method. For this reason the staminate blossoms of such 

 plants far outnumber the pistillate, as witnessed by the fact that 

 long hanging staminate catkins, from which one can dislodge a 

 cloud of fine yellow dust by a touch, are familiar to everybody in 

 Birches, Alders, Poplars, Butternuts, and other trees in the 

 spring; while the pistillate blossoms, which commonly occur on 



