UNITED STATES DEPARTMENT OF AGRICULTURE 

 BULLETIN No. 289 



Contribution from the Bureau of Plant Industry 

 WM. A. TAYLOR, Chief 



Washington, D. C. 



PROFESSIONAL PAPER 



September 21, 1915 



RED-CLOVER SEED PRODUCTION: 



POLLINATION STUDIES 



By 



J. M. WESTGATE, Agronomist, and H. S. COE, Scientific Assistant, Office 



of Forage-Crop Investigations, in Collaboration with A. T. WIANCKO 



and F. E. ROBBINS, of the Indiana Agricultural Experiment 



Station, and H. D. HUGHES, L. H. PAMMEL, and 



J. N. MARTIN, of the Iowa Agricultural 



Experiment Station 



CONTENTS 



Pago 



Introduction 1 



Previous Investigations on the Pollina- 

 tion of Red Clover 2 



Outline of Pollinating Experiments . . 5 



Structure of the Red-Clover Flower . . 5 

 Length of the Corolla Tube of Red-Clover 



Flowers 7 



Development of the Flowers of Red 



Clover 7 



Fertilization of Red-Clover Flowers . . 10 



Potency of Pollen in Self -Pollination . . 10 



Cross -Pollination and Self-Pollination of 



Red Clover 11 



Artificial Manipulation of Clover Heads . 12 

 Bumblebees as Cross-Pollinators of Red 



Clover 17 



Honeybees as Cross-Pollinators of Red 



Clover 18 



Mechanical Cross-Pollinators of Red 



Clover 20 



Summary 26 



Literature Cited 29 



' 



WASHINGTON 



GOVERNMENT PRINTING OFFICE 



1915 



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