57 ., 

 twelve of the Newman plum at Cornell University had a 

 perfect pistil. I have made careful observations on this 

 point in our own Plum-trees during the present season and 

 find a marked diflference in varieties , as to the percentage of 

 perfect pistils." 



The insects most common on the plum are honey bees 

 and other small Hymenoptera and, Diptera- During the 

 evening it is abundantly visited by cut worm moths. 



Choke Cherry '^''^ white flowers, borne in long racemes, 

 are conspicuous. Py-unus Virginiana, L., 

 is likewise proterogynous. Self-pollination as well as cross- 

 pollination occurs. Prunus serotina Elir., which flower sev- 

 eral weeks later, has the same general arrangements and 

 like the flowers of choke cherry, have a somewhat disagree- 

 able odor, which accounts for the large number of Diptera 

 .which visit it. 



Waskinffton Thorn, The white flowers are borne 

 in corymbs and are very conspicuous. They are 

 proterogynous. The nectar is secreted in the re- 

 ceptacular tube and is not concealed. It is visited by many 

 Diptera and small Hymenoptera, among them the honey bee, 

 also some Coleoptera and Lepidoptera. Of the four species, 

 Crataegus punctata Jacq. C, coccinea, L. , O. mollis and 

 C. tomentosa, no two flower at the same time about Ames. 

 Wild Crab- This blooms in and about Ames about 

 the middle of May. Pyrus coronaria, L. is one 

 of the most interesting of our native plants. The large, 

 showy and attractive purple-coloi'ed corollas are attractive to 

 insects because of the delightful fragrance. The filaments 

 of the numerous stamens form a circle about the summit of 

 the receptacle tube. These are alfco directed upwards and 



