UNITED STATES DEPARTMENT OF AGRICULTURE 
DEPARTMENT BULLETIN No. 1450 
Washington, D. C. 
March, 1927 
THE LIFE HISTORY OF TIMOTHY 
By Morgan W. Evans, Associate Agronomist, Office of Forage Crops, Bureau 
of Plant Industry 
CONTENTS 
Page 
Introduction 1 
Geographical distribution^ 2 
Economic importance 2 
Definitions 2 
Growth of the timothy plant 3 
The seedling 5 
Vegetative reproduction 7 
The shoot 10 
Growth in length of stem 10 
Two types of timothy shoots 13 
Roots 27 
Depth to which timothy roots 
grow 27 
Period during which timothy 
roots continue growth 27 
The haplocorm 28 
Names which have been applied 
to the haplocorm 29 
Time when the haplocorm makes 
its growth 30 
Conditions under which the hap- 
locorm develops 30 
Relation of the haplocorm to 
vegetative reproduction 31 
Page 
Leaves 32 
The prophvllum 32 
The leaf sheaths and blades 32 
The number of leaves on timo- 
thy shoots 33 
Habits of growth of the leaves- 35 
The inflorescence 36 
Growth of the head 37 
Length of timothy heads 38 
Time when timothy florets bloom 
and seeds mature 38 
The flowering habits of timothy. 38 
Proliferation in timothy 41 
Effect of length of day on gVowth of 
timothy . 45 
Growth through the winter with 
normal period of light 45 
Growth under long and short 
daily periods of illumination- 48 
Different phases of growth in 
relation to photoperiodism 49 
Summary 49 
Literature cited 53 
INTRODUCTION 
The data on which this bulletin is based have been obtained in a 
life-history study of timothy (PJdeum- pratense L.). which has been 
conducted, as time has been available, through a period of 12 vears, 
from 1912 to 1924. 1 The greater part of the work was done at the 
timothy-breeding field station, which is conducted cooperatively by 
J In May, 1920, a thesis by the writer entitled "The Life Historv of Timothy" was 
placed on hie m the library of George Washington University. This paper represents the 
original thesis, which has been rewritten and to which considerable new data have been 
added. 
The writer wishes to acknowledge aid that has been received from different sources. 
References to various publications consulted are presented in the " Literature cited." 
Helpful criticisms and suggestions have been received from Albert Mann, of the Carnegie 
Institution of Washington: Mrs. Agnes Chase. Lyman Carrier, G. N. Collins. C. V. Piper, 
and especially R. A. Oakley, of the United States Department of Agriculture. Without 
Their cooperation and also that of other persons not mentioned in this list this bulletin 
could not have been completed in its present form, 
4730 c 
