42 
BULLETIN 1450, tl. S. DEPARTMENT OP AGRICULTURE 
is a botanical specimen of Phleum pratense with several proliferat- 
ing florets, collected by Mrs. Agnes Chase along a woodland path at 
Riverdale, Md., July 4, 1912. In both herbariums all or nearly all 
other specimens of Phleum pratense with proliferating florets were 
collected during the fall months. 
It has been observed that timothy plants with proliferating in- 
florescences are more numerous in some seasons than in others. In 
the fall of 1919 very few proliferations could be found on the 
timothy plants growing on the timotln T -breeding field station at 
North Ridgeville, Ohio, while in the fall of 1920 they were quite 
numerous there. 
The extent to which proliferation in timothy occurs apparently 
varies with differences in the cultural conditions under which the 
plants are grown. A record made on November 6, 1920, shows that 
in a series of broadcast plats of ordinary timothy on the station, 9.8 
per cent of the growing heads had proliferations, whereas in a 
near-by series of cultivated row plats of plants grown from the 
same lot of seed which was sown in the broadcast plats, 35.5 per cent 
of the heads had proliferations. 
On November 9, 1920, a record was made of the number and per- 
centage of growing heads with proliferations on plants in a series of 
row plots of timothy selections all grown under the same cultural 
conditions. All plants in each one of the rows were propagated 
from seed of a single plant. These records are presented in Table 18. 
Table 18. — Number and percentage of heads with proliferations in row plots 
of different selections of timothy 
F. C. I. No. 
Number of heads 
with — 
Total 
number 
of heads 
Percentage 
of heads 
Prolifer- 
ations 
No prolif- 
erations 
with pro- 
liferations 
9219 - 
16 
15 
1 
1 
6 
10 
19 

35 
23 
27 
13 
35 
15 
36 
24 
33 
23 
45.71 
9220 .__ - — _ 
100. 00 
9327 ._ . - 
2.77 
9334 _ _ - - 
4. 16 
9335 - ._____'__ 
18. 18 
9822 - 
43.47 
The data show that there were much larger proportions of heads 
with proliferations in the plats of some selections than of others. 
These varying proportions may possibly be explained by different 
inherent tendencies in the plants. Another possible explanation is 
that, since not all of them bloom and mature at the same time, some 
of the selections ma}^ have been at the proper stage of development 
for proliferation to occur, while others either had not arrived at or 
else had passed that stage when conditions external to the plants 
were right to induce proliferation in timothy. 
A shoot with proliferating florets is frequently more or less ab- 
normal in other respects, having parts of the head bare of florets 
or having the base of the head partially inclosed in the sheath of 
the upper leaf of the shoot, which not infrequently has more leaves 
growing from the culm than typical shoots which produce heads in 
midsummer. A late shoot of this kind is shown in Plate 6, C. 
