CHAPTER X I 

 OUR NUT TREES 



EVERY tree bears fruit and the fruits are much 

 diversified in form and appearance. In the 

 Birch it is a cylindrical catkin which disin- 

 tegrates and allows the seeds to be scattered by the 

 wind; in the Willow and Poplar it is also a slender 

 catkin which opens and the seeds with their tuft of 

 fluffy hairs are carried long distances by the air cur- 

 rents. In the Elm the fruit is a light, winged vesicle 

 adapted for wind transportation, and in the Maple 

 it is a two-winged keylike affair also disseminated by 

 the wind. In the Crabapple family and others it is 

 pulpy and attractive to birds and animals who eat 

 the fruit but do not digest the seeds which are 

 ejected in their excrement, usually at some distance 

 from the parent trees. In the Chestnut it is a spiny 

 burr which clings to the furry coats of animals and 

 is thus distributed. In the Walnut and Hickory it 

 is a globose structure having a thin outer coat con- 

 taining an unpalatable bitter principle and a hard- 

 shelled nut within. Trees producing dry or winged 

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