36 
BULLETIN 1450, U. S. DEPARTMENT OF AGRICULTURE 
On the other hand, it has been observed that during the winter 
months, when the plants are more or less dormant, leaves may remain 
green for a considerably longer time. On each one of 10 timothy 
shoots observed November 27, 1920, there was a partially opened leaf. 
On March 14, 1921, 107 days later, these same leaves were entirely 
open and each blade was nearly or entirely green. On another plant 
w T hich was observed November 11, 1915, and again May 1, 1916, 172 
days later, about one-half of the blade of a leaf which was partially 
unfolded on the former date was still green, though of a rather 
yellow-green color, when it was observed on the latter date. 
FREQUENCY AT WHICH NEW LEAVES APPEAR 
The frequency at which new leaves appeared on three groups of 
timothy shoots observed at different times in the growing season is 
shown in Table 17. The shoots in Group 1 were growing in the field 
from seeds sown September 20 and in Group 2 from seeds sown Sep- 
tember 13. The shoots in Group 3 were growing on plants in an old 
meadow. 
Table 17.- 
-Frequency at ivhich new timothy leaves appeared on three different 
groups of shoots 
Group 
Number 
of shoots 
in group 
Period over which record extended 
Length of 
period 
(days) 
Average 
number 
of new 
leaves 
appearing 
per shoot 
Frequency 
at which 
new leaves 
appeared 
(days) 
No. 1 
25 
10 
5 
Sept. 20 to Oct. 30„ 
40 
87 
41 
3.0 
6.2 
4.2 
13.3 
No. 2 
Sept. 13 to Dec. 9 
14.0 
No. 3 
Apr. 18 to May 29„ 
9.8 
During May and June, 1916, on 14 other timothy shoots, which 
at that time were making a relatively rapid growth in length, the 
average time elapsing from the appearance of the third and that of 
the adjoining, next to the upper, leaf of the culm was 9.1 days. The 
average interval from the appearance of the next to the upper leaf 
and that of the upper leaf was 8.1 days. 
On five timothy plants grown from January 5 to April 4, 1922, 
in a greenhouse where the temperature ranged from 48 to 60° F., 
an average interval of 8.7 days elapsed between the appearance of 
successive leaves on the shoots which were observed. 
The records which have been presented show that during the 
growing season a new timothy leaf appears on timothy shoots about 
once every 8 to 14 days. The leaves appear with the greatest fre- 
quency when the plants are making their most vigorous growth. 
THE INFLORESCENCE 
Since the name " head " is the usual agricultural term for the in- 
florescence of timothy, it seems better to follow common usage, even 
though this name may not have been generally adopted in botanical 
literature. 
The head is a very contracted panicle. There are on it a very 
large number of subsessile spikelets, crowded closely together, ex- 
