THE PLUM IN KANSAS. 33 



THE POLLINATION OF PLUMS. 



By Peof. F. a. Waugh, Horticulturist at Agricultural College Experiment Station, 



Burlington, Vt. 



I. SUMMARY. 



Plums are very uncertain in setting fruit. A part of tiiis uncer- 

 tainty seems to be due to lack of proper cross-pollination. To secure 

 cross-pollination, plums of different varieties should be closely planted, 

 or scions of different varieties should be set into the tops of trees 

 which do not bear satisfactory crops of fruit. 



Cross-pollination in plums is provided for by several natural adap- 

 tations, especially by the defectiveness of flower j)arts and by the 

 sterility of certain varieties toward their own pollen. 



' American varieties of cultivated plums have arisen from several 

 distinct botanical species. These varieties retain more or less the 

 characters of the parent species, and thus may be judged to some 

 extent by their parentage. It is thought that the botanical relation- 

 ships of varieties will prove to be the best guide to their affinities in 

 cross-pollination. 



The economic characters of these groups may be generalized as 

 follows: FiUTopean {Pnuius doinestica). — Hardy, best and most 

 salable fruit ; perfect pistils, not good pollen bearers. Myrobalan. — 

 Used as stock, but losing in favor, being supplemented by Marianna 

 and American varieties. Japanese. — Comparatively new ; relative 

 value uncertain ; several varieties practically hardy. American group. 

 — The Western wild plum, very hardy, fruit good but inferior to 

 European ; good stocks ; very delicate sexually, usually requires cross- 

 pollination. Eastern forms (var. nigra) are even more hardy than 

 western forms, range further north ; stronger pistils, weaker pollen 

 bearers. Wild Goose group. — About as hardy as Japanese plums, 

 thought to need cross-pollination and to be weak pollen bearers. 

 Marianna. — Probably a hybrid; sexually weak; uncertain bearer, chiefly 

 used as stock. Chickasaw. — Of southern origin ; many prolific and 

 desirable varieties. 



Eminent horticulturists and botanists agree in the general desira- 

 bility of cross-i3ollination in plums. 



Although we have gained some knowledge as to the pollination of 

 plums, there are yet many questions of practical importance and theo- 

 retical interest open to investigation. It is hoped that this bulletin 

 will call attention to some of these unanswered questions and direct the 

 reader to futher observation and reflection. 

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