LIFE HISTORY OF TIMOTHY 13 
increased only slightly in length after that date. The combined 
length of the fifth and sixth elongated internodes on June 5 was 
less than that of any one of the four lower internodes. Later, 
when the lower internodes % had ceased to increase in length, the 
fifth and sixth made their most rapid growth. The upper one con- 
tinued to grow after each of the five internodes below it had attained 
its full length. 
The manner in which the growth in length of the stems takes 
place, as well as some other phases of growth in the wheat plant 
(Triticum aestivunv L.). very closely parallels the manner in which 
the same phases of growth occur in timothy {28, p. 83). 
TWO TYPES OF TIMOTHY SHOOTS 
That shoots of grasses may produce an inflorescence or be sterile 
has long been recognized b}^ botanists (13, p. 2 ; 31, p. 3). 
In addition to the fact that they do not produce inflorescences, 
sterile shoots differ from fertile ones in the following ways: (1) The 
stem of a sterile shoot is comparatively short and slender; (2) a 
sterile shoot may continue its growth during the late summer and 
fall, while on a fertile shoot all leaves become dry by the time the 
seeds mature in midsummer; (3) the number, of elongated inter- 
nodes and leaves on the culm of a sterile shoot becomes larger, in 
late summer or in fall, than on a fertile shoot. 
A timothy plant with a number of shoots of each type is shown in 
Plate 5, A. _ 
The relative proportions of fertile and sterile shoots in meadows 
vary widely under different conditions. In some meadows there are 
two or three times as many fertile shoots as there are sterile ones, 
while in other meadows the proportions are reversed; usually the 
relative proportions of the two types are more nearly equal. 
FACTORS AFFECTING RELATIVE NUMBER AND PROPORTION OF EACH KIND OF 
SHOOT 
The relative number and proportion of fertile or sterile shoots in 
any timothy meadow may depend upon one or more of several 
factors, all of which may be classed in two main groups. 
(1) Cultural conditions. Some of the most important of these 
conditions are: (a) Age of the meadow; (b) available space in 
which the plants may develop; (c) quality of the soil. 
(2) Hereditary tendencies of the plants of different varieties. 
CULTURAL CONDITIONS 
The results of some experiments described in the following para- 
graphs show that the number and proportion of fertile timothy 
shoots are larger in meadows where the cultural conditions are 
favorable for a vigorous growth than where conditions are less 
favorable. 
Age of the meadow. — Two series of experiments have been con- 
ducted in broadcast plats of ordinary timothy, from which records 
were obtained in regard to the relative numbers and proportions of 
the two types of shoots in them from year to year as the plats became 
older. 
