26 The Bulletin. 



They are very minute at first, but if examined carefully the form 

 of each little nut can be seen, crowned with its short, sticky, plume- 

 like stigma. See Fig. 13. 



FERTILE AND STERILE BLOOM. 



After a most extended study of biology, the great Darwin crystal- 

 lized one of his most erudite observations on nature into the fol- 

 lowing words: "Nature abhors self-fertilization." Nowhere is the 

 truth of this statement more evident than in the vegetable world. 

 Nature does abhor self-fertilization, and she takes means to prevent 

 it. The monoecious inflorescence of the pecan tree is an evidence of 

 this fact. By the placing of the stamens and pistils in separate flowers 

 on different parts of the tree instead of in the same flower, it is evi- 

 dent that nature intended pecan blooms to be cross and not self 

 fertilized. It is well known that cross-fertilization almost invariably 

 produces more vigorous offspring than self-fertilization. To further 

 avoid self-fertilization, sometimes the stamens ripen and shed their 

 pollen before the pistils are sufficiently developed to be pollinated. 

 This is common throughout the plant world and is known to botanists 

 as proterandry . The phenomenon is well illustrated in the sunflower 

 and other compositous plants. Sometimes the pistils in plants ripen 

 and are fertilized by outside pollen before their own anthers are 

 developed. This is known as proterogyny. It has been shown by Dr. 

 Trelease, of Shaw's Garden, St. Louis, that there is evidence of 

 proterandry in certain varieties of pecans. It is probable, too, that 

 with some varieties the other condition may be present. The in- 

 dustry is yet too young and large variety collections of pecans too 

 scarce to make it possible to have all these points verified. The 

 next decade or so of pecan growing will doubtless clear up many 

 of these obscure points. We have, however, sufficient data to know 

 that it is not wise to plant single varieties of pecan trees in solid 

 orchard blocks. There is a much better chance for perfect pollination 

 when they are planted in alternate rows, as well as surer prospects 

 of a crop. 



In spite of the staminate catkins appearing first, they do not 

 usually mature until the pistillate flowers are ready for pollination. 

 The pendulous staminate catkins switch about in the wind and fill 

 the air with their copious, dust-like pollen, and the sticky stigmas 

 of the pistillate flowers hold it as it comes in contact with them. 

 The pollen from one pecan tree centrally situated may be carried by 

 the wind so as to fertilize the blossoms of many trees about it. 



There is still another vegetable phenomenon which may be present 

 in pecan trees ; that is the inability of the pollen of a tree to fertilize 

 its own pistils. This is quite common with apples and other fruits. 

 This same pollen, though perfectly sterile with its own blossoms, may 



