52 BULLETIN 1450, TJ. S. DEPARTMENT OF AGRICULTURE 
appears until it becomes dry. During the late fall and winter 
months, when the plants are more or less dormant, the leaves remain 
green for a considerably longer time. 
On any growing shoot there are usually at any time from about 
four to six leaves with green or partially green blades until a short 
time before the shoot completes its growth, when the number of 
green leaves begins to diminish. 
The term " head " is applied to the inflorescence of timothy, since it 
is the name in general use by farmers and by agricultural writers. 
The rudimentary head may be readily distinguished early in the 
spring within the leaves of a young shoot. The head practically 
completes its growth in length before it emerges from the sheath of 
the upper leaf. Under conditions like those in northern Ohio the 
florets begin to bloom late in June, when the shoot has grown some- 
what more than half of its final length, and the seeds mature late 
in July or early in August. Although the available evidence in- 
dicates that timothy is commonly cross-pollinated, the florets are 
not wholly self-sterile, since relatively small proportions of them 
produce seeds when the heads are inclosed in paper sacks throughout 
the blooming period. 
When soil and climatic conditions are favorable for growth 
throughout the season, heads appear on shoots of timothy plants 
in smaller numbers at any time during the autumn. Heads on 
these shoots are frequently more or less abnormal, especially during 
the late fall. Proliferation may occur in various forms, usually 
manifesting itself by the modification of a single bract — the lemma — 
which appears as a small leaf. Less frequently the proliferation re- 
sembles a vegetative shoot, called a proliferous shoot. If partially 
covered with soil, one of these proliferous shoots will readily root 
and continue growth as a plant. Other forms of proliferation, such 
as elongation of the rachilla, occasionally develop. 
Different phases of growth in timothy respond in different ways 
to variations in the number of hours of light to which the plants 
are exposed each day. The growth of leaves proceeds at much the 
same rate, if temperature and soil conditions are favorable, whether 
the days are relatively long or short. Elongation of internodes of 
the culms does not occur when the plants are exposed to light for 
7 hours each day. When, however, plants are grown under favorable 
conditions in a greenhouse during the winter and early spring, with 
the normal number of hours of light each day, elongation of the 
internodes begins to take place several weeks earlier than on plants 
in the field. The development of the inflorescence is more sensitive 
in its response to the daily period of illumination. Heads appear 
and florets bloom on plants which make vegetative growth in the 
greenhouse during the winter and early spring at practically the 
same time as on plants which remain in the field in a more or less 
dormant condition during the winter months. 
